Common Weakness Enumeration

CWE-59

Allowed

Improper Link Resolution Before File Access ('Link Following')

Abstraction: Base · Status: Draft

The product attempts to access a file based on the filename, but it does not properly prevent that filename from identifying a link or shortcut that resolves to an unintended resource.

1992 vulnerabilities reference this CWE, most recent first.

GHSA-HC4R-GJ92-39G7

Vulnerability from github – Published: 2022-05-17 03:47 – Updated: 2022-05-17 03:47
VLAI
Details

svnwcsub.py in Subversion 1.8.0 before 1.8.3, when using the --pidfile option and running in foreground mode, allows local users to gain privileges via a symlink attack on the pid file. NOTE: this issue was SPLIT due to different affected versions (ADT3). The irkerbridge.py issue is covered by CVE-2013-7393.

Show details on source website

{
  "affected": [],
  "aliases": [
    "CVE-2013-4262"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-59"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2014-07-28T19:55:00Z",
    "severity": "LOW"
  },
  "details": "svnwcsub.py in Subversion 1.8.0 before 1.8.3, when using the --pidfile option and running in foreground mode, allows local users to gain privileges via a symlink attack on the pid file.  NOTE: this issue was SPLIT due to different affected versions (ADT3). The irkerbridge.py issue is covered by CVE-2013-7393.",
  "id": "GHSA-hc4r-gj92-39g7",
  "modified": "2022-05-17T03:47:56Z",
  "published": "2022-05-17T03:47:56Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2013-4262"
    },
    {
      "type": "WEB",
      "url": "https://subversion.apache.org/security/CVE-2013-4262-advisory.txt"
    },
    {
      "type": "WEB",
      "url": "http://www.oracle.com/technetwork/topics/security/bulletinoct2015-2511968.html"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}

GHSA-HC7X-M44M-XHXQ

Vulnerability from github – Published: 2025-07-08 18:31 – Updated: 2025-09-15 18:31
VLAI
Details

Improper link resolution before file access ('link following') in Windows Update Service allows an authorized attacker to elevate privileges locally.

Show details on source website

{
  "affected": [],
  "aliases": [
    "CVE-2025-48799"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-59"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2025-07-08T17:15:42Z",
    "severity": "HIGH"
  },
  "details": "Improper link resolution before file access (\u0027link following\u0027) in Windows Update Service allows an authorized attacker to elevate privileges locally.",
  "id": "GHSA-hc7x-m44m-xhxq",
  "modified": "2025-09-15T18:31:05Z",
  "published": "2025-07-08T18:31:45Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2025-48799"
    },
    {
      "type": "WEB",
      "url": "https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-48799"
    },
    {
      "type": "WEB",
      "url": "https://www.vicarius.io/vsociety/posts/cve-2025-48799-detection-script-elevation-of-privilege-vulnerability-in-windows-update-service"
    },
    {
      "type": "WEB",
      "url": "https://www.vicarius.io/vsociety/posts/cve-2025-48799-mitigation-script-elevation-of-privilege-vulnerability-in-windows-update-service"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}

GHSA-HC8W-F35H-8RRJ

Vulnerability from github – Published: 2022-09-20 00:00 – Updated: 2022-09-23 00:00
VLAI
Details

Trend Micro Security 2022 (consumer) has a link following vulnerability where an attacker with lower privileges could manipulate a mountpoint which could lead to escalation of privilege on an affected machine.

Show details on source website

{
  "affected": [],
  "aliases": [
    "CVE-2022-34893"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-59"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2022-09-19T18:15:00Z",
    "severity": "HIGH"
  },
  "details": "Trend Micro Security 2022 (consumer) has a link following vulnerability where an attacker with lower privileges could manipulate a mountpoint which could lead to escalation of privilege on an affected machine.",
  "id": "GHSA-hc8w-f35h-8rrj",
  "modified": "2022-09-23T00:00:41Z",
  "published": "2022-09-20T00:00:28Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2022-34893"
    },
    {
      "type": "WEB",
      "url": "https://helpcenter.trendmicro.com/en-us/article/tmka-11053"
    },
    {
      "type": "WEB",
      "url": "https://www.zerodayinitiative.com/advisories/ZDI-22-1175"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}

GHSA-HCM4-3MHF-GMFH

Vulnerability from github – Published: 2022-05-17 02:18 – Updated: 2022-05-17 02:18
VLAI
Details

rkhunter in rkhunter 1.3.2 allows local users to overwrite arbitrary files via a symlink attack on the /tmp/rkhunter-debug temporary file. NOTE: this is probably a different vulnerability than CVE-2005-1270.

Show details on source website

{
  "affected": [],
  "aliases": [
    "CVE-2008-4982"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-59"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2008-11-06T15:55:00Z",
    "severity": "MODERATE"
  },
  "details": "rkhunter in rkhunter 1.3.2 allows local users to overwrite arbitrary files via a symlink attack on the /tmp/rkhunter-debug temporary file. NOTE: this is probably a different vulnerability than CVE-2005-1270.",
  "id": "GHSA-hcm4-3mhf-gmfh",
  "modified": "2022-05-17T02:18:28Z",
  "published": "2022-05-17T02:18:28Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2008-4982"
    },
    {
      "type": "WEB",
      "url": "https://bugs.gentoo.org/show_bug.cgi?id=235770"
    },
    {
      "type": "WEB",
      "url": "https://bugs.gentoo.org/show_bug.cgi?id=235798"
    },
    {
      "type": "WEB",
      "url": "https://exchange.xforce.ibmcloud.com/vulnerabilities/46511"
    },
    {
      "type": "WEB",
      "url": "http://bugs.debian.org/496375"
    },
    {
      "type": "WEB",
      "url": "http://dev.gentoo.org/~rbu/security/debiantemp/rkhunter"
    },
    {
      "type": "WEB",
      "url": "http://www.openwall.com/lists/oss-security/2008/10/30/2"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}

GHSA-HF8C-7P7W-MCH5

Vulnerability from github – Published: 2022-05-17 03:27 – Updated: 2025-04-12 12:54
VLAI
Details

The abrt-hook-ccpp help program in Automatic Bug Reporting Tool (ABRT) before 2.7.1 allows local users with certain permissions to gain privileges via a symlink attack on a file with a predictable name, as demonstrated by /var/tmp/abrt/abrt-hax-coredump or /var/spool/abrt/abrt-hax-coredump.

Show details on source website

{
  "affected": [],
  "aliases": [
    "CVE-2015-5287"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-59"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2015-12-07T18:59:00Z",
    "severity": "MODERATE"
  },
  "details": "The abrt-hook-ccpp help program in Automatic Bug Reporting Tool (ABRT) before 2.7.1 allows local users with certain permissions to gain privileges via a symlink attack on a file with a predictable name, as demonstrated by /var/tmp/abrt/abrt-hax-coredump or /var/spool/abrt/abrt-hax-coredump.",
  "id": "GHSA-hf8c-7p7w-mch5",
  "modified": "2025-04-12T12:54:26Z",
  "published": "2022-05-17T03:27:18Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2015-5287"
    },
    {
      "type": "WEB",
      "url": "https://github.com/abrt/abrt/commit/3c1b60cfa62d39e5fff5a53a5bc53dae189e740e"
    },
    {
      "type": "WEB",
      "url": "https://bugzilla.redhat.com/show_bug.cgi?id=1266837"
    },
    {
      "type": "WEB",
      "url": "https://www.exploit-db.com/exploits/38832"
    },
    {
      "type": "WEB",
      "url": "http://packetstormsecurity.com/files/154592/ABRT-sosreport-Privilege-Escalation.html"
    },
    {
      "type": "WEB",
      "url": "http://rhn.redhat.com/errata/RHSA-2015-2505.html"
    },
    {
      "type": "WEB",
      "url": "http://www.openwall.com/lists/oss-security/2015/12/01/1"
    },
    {
      "type": "WEB",
      "url": "http://www.oracle.com/technetwork/topics/security/linuxbulletinoct2015-2719645.html"
    },
    {
      "type": "WEB",
      "url": "http://www.securityfocus.com/bid/78137"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}

GHSA-HFP4-CQ95-QV3Q

Vulnerability from github – Published: 2022-05-17 05:01 – Updated: 2022-05-17 05:01
VLAI
Details

asr in Oracle Auto Service Request in Oracle Support Tools before 4.3.2 allows local users to modify arbitrary files via a symlink attack on a predictable filename in /tmp.

Show details on source website

{
  "affected": [],
  "aliases": [
    "CVE-2013-1495"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-59"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2013-03-18T21:55:00Z",
    "severity": "MODERATE"
  },
  "details": "asr in Oracle Auto Service Request in Oracle Support Tools before 4.3.2 allows local users to modify arbitrary files via a symlink attack on a predictable filename in /tmp.",
  "id": "GHSA-hfp4-cq95-qv3q",
  "modified": "2022-05-17T05:01:49Z",
  "published": "2022-05-17T05:01:49Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2013-1495"
    },
    {
      "type": "WEB",
      "url": "http://seclists.org/fulldisclosure/2013/Feb/159"
    },
    {
      "type": "WEB",
      "url": "http://www.mandriva.com/security/advisories?name=MDVSA-2013:150"
    },
    {
      "type": "WEB",
      "url": "http://www.oracle.com/technetwork/topics/security/cpuapr2013-1899555.html"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}

GHSA-HFQ3-3QV2-X5X2

Vulnerability from github – Published: 2023-02-13 09:30 – Updated: 2023-02-23 06:30
VLAI
Details

Dell Command | Integration Suite for System Center, versions before 6.4.0 contain an arbitrary folder delete vulnerability during uninstallation. A locally authenticated malicious user may potentially exploit this vulnerability leading to arbitrary folder deletion.

Show details on source website

{
  "affected": [],
  "aliases": [
    "CVE-2023-24572"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-59"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2023-02-13T08:15:00Z",
    "severity": "LOW"
  },
  "details": "Dell Command | Integration Suite for System Center, versions before 6.4.0 contain an arbitrary folder delete vulnerability during uninstallation. A locally authenticated malicious user may potentially exploit this vulnerability leading to arbitrary folder deletion.",
  "id": "GHSA-hfq3-3qv2-x5x2",
  "modified": "2023-02-23T06:30:19Z",
  "published": "2023-02-13T09:30:23Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2023-24572"
    },
    {
      "type": "WEB",
      "url": "https://www.dell.com/support/kbdoc/en-us/000207931/dsa-2023-032"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N",
      "type": "CVSS_V3"
    }
  ]
}

GHSA-HFX9-J834-CMXW

Vulnerability from github – Published: 2024-11-23 03:31 – Updated: 2024-11-23 03:31
VLAI
Details

F-Secure Total Link Following Local Privilege Escalation Vulnerability. This vulnerability allows local attackers to escalate privileges on affected installations of F-Secure Total. User interaction on the part of an administrator is required to exploit this vulnerability.

The specific flaw exists within the WithSecure plugin hosting service. By creating a symbolic link, an attacker can abuse the service to create a file. An attacker can leverage this vulnerability to escalate privileges and execute arbitrary code in the context of SYSTEM. Was ZDI-CAN-23005.

Show details on source website

{
  "affected": [],
  "aliases": [
    "CVE-2024-7240"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-59"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2024-11-22T22:15:16Z",
    "severity": "HIGH"
  },
  "details": "F-Secure Total Link Following Local Privilege Escalation Vulnerability. This vulnerability allows local attackers to escalate privileges on affected installations of F-Secure Total. User interaction on the part of an administrator is required to exploit this vulnerability.\n\nThe specific flaw exists within the WithSecure plugin hosting service. By creating a symbolic link, an attacker can abuse the service to create a file. An attacker can leverage this vulnerability to escalate privileges and execute arbitrary code in the context of SYSTEM. Was ZDI-CAN-23005.",
  "id": "GHSA-hfx9-j834-cmxw",
  "modified": "2024-11-23T03:31:58Z",
  "published": "2024-11-23T03:31:58Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2024-7240"
    },
    {
      "type": "WEB",
      "url": "https://www.zerodayinitiative.com/advisories/ZDI-24-1012"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.0/AV:L/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}

GHSA-HG88-V3CW-3QRH

Vulnerability from github – Published: 2026-05-29 19:45 – Updated: 2026-05-29 19:45
VLAI
Summary
Sparkle: Binary delta apply intermediate-symlink traversal in malicious .delta
Details

Summary

Binary delta apply intermediate-symlink traversal in malicious .delta

Autoupdate/SUBinaryDeltaApply.m enforces relativePath.pathComponents containsObject:@".." and rejects writes whose immediate parent directory IS itself a symbolic link, but does not detect symlinks deeper in the relative path. Autoupdate/SPUSparkleDeltaArchive.m's extractItem: will create symlinks in the destination tree from archive content (no .. check on the symlink target), and a subsequent Extract item targeting <symlink>/foo/bar then escapes the destination tree via fopen(path, "wb") because the kernel resolves the intermediate symlink during the open call.

This is a defense-in-depth issue: exploitation requires a maliciously-crafted .delta that passes EdDSA signature verification, i.e. EdDSA private-key compromise. With the AppInstaller running as root for system-domain installs, it gives the holder of a stolen signing key arbitrary file write at root level via the delta-apply path, which is a strictly broader primitive than the "drop-in replacement bundle" install they would otherwise have.

Affected versions: 1.x (master branch), 2.x branch including 2.9.1.

Details

Symlink writeable from archive

Autoupdate/SPUSparkleDeltaArchive.m:557-678's extractItem: handles symlinks if the archive item carries S_ISLNK(mode):

} else {
    // Link files

    if (PARTIAL_IO_CHUNK_SIZE < decodedLength) { ...too long... }
    if (decodedLength > PATH_MAX) { ...too long... }

    char buffer[PATH_MAX + 1] = {0};
    if (![self _readBuffer:buffer length:(int32_t)decodedLength]) { ... }

    NSString *destinationPath = [fileManager stringWithFileSystemRepresentation:buffer length:decodedLength];

    [fileManager removeItemAtPath:itemFilePath error:NULL];

    NSError *createLinkError = nil;
    if (![fileManager createSymbolicLinkAtPath:itemFilePath withDestinationPath:destinationPath error:&createLinkError]) {
        _error = createLinkError;
        return NO;
    }
    ...
    lchmod(itemFilePathString, mode);
}

The link's destinationPath is taken verbatim from the archive content with only a length cap; absolute paths and .. are accepted. After this item is processed, the destination tree contains a symlink that points outside it.

Parent-symlink check is shallow

Autoupdate/SUBinaryDeltaApply.m:177-207:

[archive enumerateItems:^(SPUDeltaArchiveItem *item, BOOL *stop) {
    NSString *relativePath = item.relativeFilePath;

    if ([relativePath.pathComponents containsObject:@".."]) {
        ...reject...
    }

    NSString *sourceFilePath = [source stringByAppendingPathComponent:relativePath];
    NSString *destinationFilePath = [destination stringByAppendingPathComponent:relativePath];
    {
        NSString *destinationParentDirectory = destinationFilePath.stringByDeletingLastPathComponent;
        NSDictionary<NSFileAttributeKey, id> *destinationParentDirectoryAttributes = [fileManager attributesOfItemAtPath:destinationParentDirectory error:NULL];

        // It is OK for the directory parent to not exist if it has already been removed
        if (destinationParentDirectoryAttributes != nil) {
            NSString *fileType = destinationParentDirectoryAttributes[NSFileType];
            if ([fileType isEqualToString:NSFileTypeSymbolicLink]) {
                ...reject...
            }
        }
    }
    ...
}];

Two gaps:

  1. The check inspects only destinationParentDirectory (one level up), not all intermediate components. For a relative path a/b/c.txt, the kernel resolves through any symlink at component a. attributesOfItemAtPath: with the resolved path returns attributes of the resolved-through directory, which is NSFileTypeDirectory (not NSFileTypeSymbolicLink), so the check passes.

  2. The check is skipped entirely if destinationParentDirectoryAttributes == nil (line 195). When the symlink target is to a directory that does not contain the named subpath, the parent appears not to exist and the check is skipped. The subsequent fopen(path, "wb") then creates the file along the resolved path.

Write primitive

For an item with SPUDeltaItemCommandExtract set, SUBinaryDeltaApply.m:354-365 calls [archive extractItem:item] which goes through SPUSparkleDeltaArchive.m:574-622 for regular files:

[fileManager removeItemAtPath:itemFilePath error:NULL];

char itemFilePathString[PATH_MAX + 1] = {0};
if (![itemFilePath getFileSystemRepresentation:itemFilePathString maxLength:sizeof(itemFilePathString) - 1]) { ... }

FILE *outputFile = fopen(itemFilePathString, "wb");

fopen(path, "wb") follows symlinks at every path component and creates/truncates the file at the resolved path. If <dest>/a is a symlink to /Library/LaunchDaemons (for a root install) and the relative path is a/com.attacker.plist, the call writes /Library/LaunchDaemons/com.attacker.plist.

The chmod follow-up at SUBinaryDeltaApply.m:335 (chmod(destinationFilePath.fileSystemRepresentation, sourceFileInfo.st_mode)) and SPUSparkleDeltaArchive.m:619 (chmod(itemFilePathString, mode)) likewise follows symlinks, so attacker-chosen permissions land on the attacker-chosen target.

Threat model

This primitive is reachable only when the archive can pass EdDSA signature verification, which requires either:

  • The developer's private signing key has been compromised, or
  • A separate vulnerability allows bypassing SUSignatureVerifier (none was identified in this review).

Given a stolen private key, the attacker already has the ability to push a normal full-bundle update. The delta-apply traversal grants strictly more: arbitrary file write into directories outside <destination>. When the AppInstaller runs in the system domain (root), this becomes arbitrary file write as root, which is qualitatively broader than "replace the app bundle".

It is therefore worth fixing as a defense-in-depth measure, even though the prerequisite (key compromise) is itself a worst case.

PoC

The PoC requires a valid EdDSA signature on the malicious .delta archive. With a test signing key under your control (any Sparkle test fixture key), generate a delta as follows:

  1. Construct the archive payload with two items, in this order, using the SPUSparkleDeltaArchive writer (or by hand-assembling the format described in SPUSparkleDeltaArchive.m and SPUDeltaArchiveProtocol.h):
Item 1:
  relativeFilePath = "Contents/Resources/escape"
  commands         = SPUDeltaItemCommandExtract  (= 0x02)
  mode             = S_IFLNK | 0o755             (= 0xA1ED)
  payload          = "/Library/LaunchDaemons"

Item 2:
  relativeFilePath = "Contents/Resources/escape/com.attacker.persistence.plist"
  commands         = SPUDeltaItemCommandExtract  (= 0x02)
  mode             = S_IFREG | 0o644             (= 0x81A4)
  payload          = <attacker-chosen LaunchDaemon plist bytes>
  1. Sign the archive with the test EdDSA key, publish it as a delta enclosure with matching sparkle:edSignature, and host it from a feed pointed at by a Sparkle host whose old-bundle public key matches.

  2. Trigger a system-domain install. The flow:

  3. applyBinaryDelta enumerates items.
  4. Item 1 passes the .. check (the path components are Contents, Resources, escape - no ..). The parent Contents/Resources exists in the source-copy and is a directory, not a symlink. The check passes. extractItem: for S_ISLNK(mode) calls createSymbolicLinkAtPath:withDestinationPath: and creates <dest>/Contents/Resources/escape -> /Library/LaunchDaemons.
  5. Item 2 passes the .. check. Its parent <dest>/Contents/Resources/escape resolves through the just-created symlink to /Library/LaunchDaemons, whose attributes are returned as NSFileTypeDirectory (not symlink). The check passes.
  6. extractItem: for S_ISREG(mode) does removeItemAtPath (no-op, target file does not yet exist) then fopen("<dest>/Contents/Resources/escape/com.attacker.persistence.plist", "wb"). The kernel resolves the symlink and creates /Library/LaunchDaemons/com.attacker.persistence.plist.
  7. The hash check at the end of applyBinaryDelta (getRawHashOfTreeWithVersion(afterHash, finalDestination, ...)) is computed only against finalDestination. The file dropped at /Library/LaunchDaemons/ is outside that tree and does not affect the hash. The hash check still passes (or, if it does not because the dest tree is missing the file, the dropped LaunchDaemon plist is still left behind - destination cleanup at line 471 only removes finalDestination, not the escape target).

  8. Observed result: a root-owned LaunchDaemon plist exists at /Library/LaunchDaemons/com.attacker.persistence.plist. On next reboot it is launched as root.

A simpler proof-of-concept that does not require a system-domain install: target a user-writable directory (e.g. ~/Library/LaunchAgents/), use a user-domain Sparkle host. The same item-pair lands a user-level LaunchAgent at next login.

Impact

Defense-in-depth gap: the holder of a compromised EdDSA signing key gains a primitive (arbitrary file write at the privilege of the AppInstaller process) that exceeds what an "install a malicious bundle" path provides. For system-domain installs this is arbitrary file write as root, including locations outside the target app bundle (/Library/LaunchDaemons, /etc/... subpaths that exist as directories, /usr/local/, etc.).

Recommended fix: in SUBinaryDeltaApply.m, walk every component of relativePath and reject if any intermediate component is a symlink (or refuse to allow the archive to create symlinks during apply at all, given the limited number of legitimate use cases for symlinks inside an .app bundle and the existing lchmod already in place). Cleanup on failure should also removeTree along the symlink target, not just finalDestination.

Show details on source website

{
  "affected": [
    {
      "package": {
        "ecosystem": "SwiftURL",
        "name": "github.com/sparkle-project/Sparkle"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "last_affected": "2.9.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-47121"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-22",
      "CWE-59"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-05-29T19:45:04Z",
    "nvd_published_at": null,
    "severity": "MODERATE"
  },
  "details": "## Summary\n\nBinary delta apply intermediate-symlink traversal in malicious .delta\n\n`Autoupdate/SUBinaryDeltaApply.m` enforces `relativePath.pathComponents containsObject:@\"..\"` and rejects writes whose immediate parent directory IS itself a symbolic link, but does not detect symlinks deeper in the relative path. `Autoupdate/SPUSparkleDeltaArchive.m`\u0027s `extractItem:` will create symlinks in the destination tree from archive content (no `..` check on the symlink target), and a subsequent `Extract` item targeting `\u003csymlink\u003e/foo/bar` then escapes the destination tree via `fopen(path, \"wb\")` because the kernel resolves the intermediate symlink during the open call.\n\nThis is a defense-in-depth issue: exploitation requires a maliciously-crafted `.delta` that passes EdDSA signature verification, i.e. EdDSA private-key compromise. With the AppInstaller running as root for system-domain installs, it gives the holder of a stolen signing key arbitrary file write at root level via the delta-apply path, which is a strictly broader primitive than the \"drop-in replacement bundle\" install they would otherwise have.\n\nAffected versions: 1.x (master branch), 2.x branch including 2.9.1.\n\n## Details\n\n### Symlink writeable from archive\n\n`Autoupdate/SPUSparkleDeltaArchive.m:557-678`\u0027s `extractItem:` handles symlinks if the archive item carries `S_ISLNK(mode)`:\n\n```objc\n} else {\n    // Link files\n\n    if (PARTIAL_IO_CHUNK_SIZE \u003c decodedLength) { ...too long... }\n    if (decodedLength \u003e PATH_MAX) { ...too long... }\n\n    char buffer[PATH_MAX + 1] = {0};\n    if (![self _readBuffer:buffer length:(int32_t)decodedLength]) { ... }\n\n    NSString *destinationPath = [fileManager stringWithFileSystemRepresentation:buffer length:decodedLength];\n\n    [fileManager removeItemAtPath:itemFilePath error:NULL];\n\n    NSError *createLinkError = nil;\n    if (![fileManager createSymbolicLinkAtPath:itemFilePath withDestinationPath:destinationPath error:\u0026createLinkError]) {\n        _error = createLinkError;\n        return NO;\n    }\n    ...\n    lchmod(itemFilePathString, mode);\n}\n```\n\nThe link\u0027s `destinationPath` is taken verbatim from the archive content with only a length cap; absolute paths and `..` are accepted. After this item is processed, the destination tree contains a symlink that points outside it.\n\n### Parent-symlink check is shallow\n\n`Autoupdate/SUBinaryDeltaApply.m:177-207`:\n\n```objc\n[archive enumerateItems:^(SPUDeltaArchiveItem *item, BOOL *stop) {\n    NSString *relativePath = item.relativeFilePath;\n\n    if ([relativePath.pathComponents containsObject:@\"..\"]) {\n        ...reject...\n    }\n\n    NSString *sourceFilePath = [source stringByAppendingPathComponent:relativePath];\n    NSString *destinationFilePath = [destination stringByAppendingPathComponent:relativePath];\n    {\n        NSString *destinationParentDirectory = destinationFilePath.stringByDeletingLastPathComponent;\n        NSDictionary\u003cNSFileAttributeKey, id\u003e *destinationParentDirectoryAttributes = [fileManager attributesOfItemAtPath:destinationParentDirectory error:NULL];\n\n        // It is OK for the directory parent to not exist if it has already been removed\n        if (destinationParentDirectoryAttributes != nil) {\n            NSString *fileType = destinationParentDirectoryAttributes[NSFileType];\n            if ([fileType isEqualToString:NSFileTypeSymbolicLink]) {\n                ...reject...\n            }\n        }\n    }\n    ...\n}];\n```\n\nTwo gaps:\n\n1. The check inspects only `destinationParentDirectory` (one level up), not all intermediate components. For a relative path `a/b/c.txt`, the kernel resolves through any symlink at component `a`. `attributesOfItemAtPath:` with the resolved path returns attributes of the resolved-through directory, which is `NSFileTypeDirectory` (not `NSFileTypeSymbolicLink`), so the check passes.\n\n2. The check is skipped entirely if `destinationParentDirectoryAttributes == nil` (line 195). When the symlink target is to a directory that does not contain the named subpath, the parent appears not to exist and the check is skipped. The subsequent `fopen(path, \"wb\")` then creates the file along the resolved path.\n\n### Write primitive\n\nFor an item with `SPUDeltaItemCommandExtract` set, `SUBinaryDeltaApply.m:354-365` calls `[archive extractItem:item]` which goes through `SPUSparkleDeltaArchive.m:574-622` for regular files:\n\n```objc\n[fileManager removeItemAtPath:itemFilePath error:NULL];\n\nchar itemFilePathString[PATH_MAX + 1] = {0};\nif (![itemFilePath getFileSystemRepresentation:itemFilePathString maxLength:sizeof(itemFilePathString) - 1]) { ... }\n\nFILE *outputFile = fopen(itemFilePathString, \"wb\");\n```\n\n`fopen(path, \"wb\")` follows symlinks at every path component and creates/truncates the file at the resolved path. If `\u003cdest\u003e/a` is a symlink to `/Library/LaunchDaemons` (for a root install) and the relative path is `a/com.attacker.plist`, the call writes `/Library/LaunchDaemons/com.attacker.plist`.\n\nThe `chmod` follow-up at `SUBinaryDeltaApply.m:335` (`chmod(destinationFilePath.fileSystemRepresentation, sourceFileInfo.st_mode)`) and `SPUSparkleDeltaArchive.m:619` (`chmod(itemFilePathString, mode)`) likewise follows symlinks, so attacker-chosen permissions land on the attacker-chosen target.\n\n### Threat model\n\nThis primitive is reachable only when the archive can pass EdDSA signature verification, which requires either:\n\n- The developer\u0027s private signing key has been compromised, or\n- A separate vulnerability allows bypassing `SUSignatureVerifier` (none was identified in this review).\n\nGiven a stolen private key, the attacker already has the ability to push a normal full-bundle update. The delta-apply traversal grants strictly more: arbitrary file write into directories outside `\u003cdestination\u003e`. When the AppInstaller runs in the system domain (root), this becomes arbitrary file write as root, which is qualitatively broader than \"replace the app bundle\".\n\nIt is therefore worth fixing as a defense-in-depth measure, even though the prerequisite (key compromise) is itself a worst case.\n\n## PoC\n\nThe PoC requires a valid EdDSA signature on the malicious `.delta` archive. With a test signing key under your control (any Sparkle test fixture key), generate a delta as follows:\n\n1. Construct the archive payload with two items, in this order, using the `SPUSparkleDeltaArchive` writer (or by hand-assembling the format described in `SPUSparkleDeltaArchive.m` and `SPUDeltaArchiveProtocol.h`):\n\n```\nItem 1:\n  relativeFilePath = \"Contents/Resources/escape\"\n  commands         = SPUDeltaItemCommandExtract  (= 0x02)\n  mode             = S_IFLNK | 0o755             (= 0xA1ED)\n  payload          = \"/Library/LaunchDaemons\"\n\nItem 2:\n  relativeFilePath = \"Contents/Resources/escape/com.attacker.persistence.plist\"\n  commands         = SPUDeltaItemCommandExtract  (= 0x02)\n  mode             = S_IFREG | 0o644             (= 0x81A4)\n  payload          = \u003cattacker-chosen LaunchDaemon plist bytes\u003e\n```\n\n2. Sign the archive with the test EdDSA key, publish it as a delta enclosure with matching `sparkle:edSignature`, and host it from a feed pointed at by a Sparkle host whose old-bundle public key matches.\n\n3. Trigger a system-domain install. The flow:\n   - `applyBinaryDelta` enumerates items.\n   - Item 1 passes the `..` check (the path components are `Contents`, `Resources`, `escape` - no `..`). The parent `Contents/Resources` exists in the source-copy and is a directory, not a symlink. The check passes. `extractItem:` for `S_ISLNK(mode)` calls `createSymbolicLinkAtPath:withDestinationPath:` and creates `\u003cdest\u003e/Contents/Resources/escape -\u003e /Library/LaunchDaemons`.\n   - Item 2 passes the `..` check. Its parent `\u003cdest\u003e/Contents/Resources/escape` resolves through the just-created symlink to `/Library/LaunchDaemons`, whose attributes are returned as `NSFileTypeDirectory` (not symlink). The check passes.\n   - `extractItem:` for `S_ISREG(mode)` does `removeItemAtPath` (no-op, target file does not yet exist) then `fopen(\"\u003cdest\u003e/Contents/Resources/escape/com.attacker.persistence.plist\", \"wb\")`. The kernel resolves the symlink and creates `/Library/LaunchDaemons/com.attacker.persistence.plist`.\n   - The hash check at the end of `applyBinaryDelta` (`getRawHashOfTreeWithVersion(afterHash, finalDestination, ...)`) is computed only against `finalDestination`. The file dropped at `/Library/LaunchDaemons/` is outside that tree and does not affect the hash. The hash check still passes (or, if it does not because the dest tree is missing the file, the dropped LaunchDaemon plist is still left behind - destination cleanup at line 471 only removes `finalDestination`, not the escape target).\n\n4. Observed result: a root-owned LaunchDaemon plist exists at `/Library/LaunchDaemons/com.attacker.persistence.plist`. On next reboot it is launched as root.\n\nA simpler proof-of-concept that does not require a system-domain install: target a user-writable directory (e.g. `~/Library/LaunchAgents/`), use a user-domain Sparkle host. The same item-pair lands a user-level LaunchAgent at next login.\n\n## Impact\n\nDefense-in-depth gap: the holder of a compromised EdDSA signing key gains a primitive (arbitrary file write at the privilege of the AppInstaller process) that exceeds what an \"install a malicious bundle\" path provides. For system-domain installs this is arbitrary file write as root, including locations outside the target app bundle (`/Library/LaunchDaemons`, `/etc/...` subpaths that exist as directories, `/usr/local/`, etc.).\n\nRecommended fix: in `SUBinaryDeltaApply.m`, walk every component of `relativePath` and reject if any intermediate component is a symlink (or refuse to allow the archive to create symlinks during apply at all, given the limited number of legitimate use cases for symlinks inside an `.app` bundle and the existing `lchmod` already in place). Cleanup on failure should also `removeTree` along the symlink target, not just `finalDestination`.",
  "id": "GHSA-hg88-v3cw-3qrh",
  "modified": "2026-05-29T19:45:04Z",
  "published": "2026-05-29T19:45:04Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/sparkle-project/Sparkle/security/advisories/GHSA-hg88-v3cw-3qrh"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/sparkle-project/Sparkle"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:N/I:H/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Sparkle: Binary delta apply intermediate-symlink traversal in malicious .delta"
}

GHSA-HG9W-23HG-6PFV

Vulnerability from github – Published: 2026-02-03 18:30 – Updated: 2026-02-05 15:31
VLAI
Details

The ZSPACE Q2C NAS contains a vulnerability related to incorrect symbolic link following. Attackers can format a USB drive to ext4, create a symbolic link to its root directory, insert the drive into the NAS device's slot, and then access the USB drive's directory mounted on the NAS using the Samba protocol. This allows them to obtain all files within the NAS system and tamper with those files.

Show details on source website

{
  "affected": [],
  "aliases": [
    "CVE-2025-69431"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-59"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-02-03T18:16:16Z",
    "severity": "CRITICAL"
  },
  "details": "The ZSPACE Q2C NAS contains a vulnerability related to incorrect symbolic link following. Attackers can format a USB drive to ext4, create a symbolic link to its root directory, insert the drive into the NAS device\u0027s slot, and then access the USB drive\u0027s directory mounted on the NAS using the Samba protocol. This allows them to obtain all files within the NAS system and tamper with those files.",
  "id": "GHSA-hg9w-23hg-6pfv",
  "modified": "2026-02-05T15:31:09Z",
  "published": "2026-02-03T18:30:47Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2025-69431"
    },
    {
      "type": "WEB",
      "url": "https://www.notion.so/ZSPACE-Incorrect-Symlink-Follow-2c26cf4e528a8087ba14d9b1d31a5bb2?source=copy_link"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}

Mitigation MIT-48.1
Architecture and Design

Strategy: Separation of Privilege

  • Follow the principle of least privilege when assigning access rights to entities in a software system.
  • Denying access to a file can prevent an attacker from replacing that file with a link to a sensitive file. Ensure good compartmentalization in the system to provide protected areas that can be trusted.
CAPEC-132: Symlink Attack

An adversary positions a symbolic link in such a manner that the targeted user or application accesses the link's endpoint, assuming that it is accessing a file with the link's name.

CAPEC-17: Using Malicious Files

An attack of this type exploits a system's configuration that allows an adversary to either directly access an executable file, for example through shell access; or in a possible worst case allows an adversary to upload a file and then execute it. Web servers, ftp servers, and message oriented middleware systems which have many integration points are particularly vulnerable, because both the programmers and the administrators must be in synch regarding the interfaces and the correct privileges for each interface.

CAPEC-35: Leverage Executable Code in Non-Executable Files

An attack of this type exploits a system's trust in configuration and resource files. When the executable loads the resource (such as an image file or configuration file) the attacker has modified the file to either execute malicious code directly or manipulate the target process (e.g. application server) to execute based on the malicious configuration parameters. Since systems are increasingly interrelated mashing up resources from local and remote sources the possibility of this attack occurring is high.

CAPEC-76: Manipulating Web Input to File System Calls

An attacker manipulates inputs to the target software which the target software passes to file system calls in the OS. The goal is to gain access to, and perhaps modify, areas of the file system that the target software did not intend to be accessible.