CVE-2026-64057 (GCVE-0-2026-64057)

Vulnerability from cvelistv5 – Published: 2026-07-19 15:39 – Updated: 2026-08-05 12:38
VLAI
Title
afs: Fix the locking used by afs_get_link()
Summary
In the Linux kernel, the following vulnerability has been resolved: afs: Fix the locking used by afs_get_link() The afs filesystem in the kernel doesn't do locking correctly for symbolic links. There are a number of problems: (1) It doesn't do any locking around afs_read_single() to prevent races between multiple ->get_link() calls, thereby allowing the possibility of leaks. (2) It doesn't use RCU barriering when accessing the buffer pointers during RCU pathwalk. (3) It can race with another thread updating the contents of the symlink if a third party updated it on the server. Fix this by the following means: (0) Move symlink handling into its own file as this makes it more complicated. (1) Take the validate_lock around afs_read_single() to prevent races between multiple ->get_link() calls. (2) Keep a separate copy of the symlink contents with an rcu_head. This is always going to be a lot smaller than a page, so it can be kmalloc'd and save quite a bit of memory. It also needs a refcount for non-RCU pathwalk. (3) Split the symlink read and write-to-cache routines in afs from those for directories. (4) Discard the I/O buffer as soon as the write-to-cache completes as this is a full page (plus a folio_queue). (5) If there's no cache, discard the I/O buffer immediately after reading and copying if there is no cache.
Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: eae9e78951bb02a7b94a9adef6e981413d13c564 , < 77ea917cbed62882a33114b1e23ededb977e4287 (git)
Affected: eae9e78951bb02a7b94a9adef6e981413d13c564 , < c0410adf3da6db46f3513411fcf95e63c2f1d1ad (git)
Create a notification for this product.
Linux Linux Affected: 6.14
Unaffected: 0 , < 6.14 (semver)
Unaffected: 7.0.11 , ≤ 7.0.* (semver)
Unaffected: 7.1 , ≤ * (original_commit_for_fix)
Create a notification for this product.
Show details on NVD website
To clipboard 

{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/afs/Makefile",
            "fs/afs/dir.c",
            "fs/afs/fsclient.c",
            "fs/afs/inode.c",
            "fs/afs/internal.h",
            "fs/afs/symlink.c",
            "fs/afs/validation.c",
            "fs/afs/yfsclient.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "77ea917cbed62882a33114b1e23ededb977e4287",
              "status": "affected",
              "version": "eae9e78951bb02a7b94a9adef6e981413d13c564",
              "versionType": "git"
            },
            {
              "lessThan": "c0410adf3da6db46f3513411fcf95e63c2f1d1ad",
              "status": "affected",
              "version": "eae9e78951bb02a7b94a9adef6e981413d13c564",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "fs/afs/Makefile",
            "fs/afs/dir.c",
            "fs/afs/fsclient.c",
            "fs/afs/inode.c",
            "fs/afs/internal.h",
            "fs/afs/symlink.c",
            "fs/afs/validation.c",
            "fs/afs/yfsclient.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.14"
            },
            {
              "lessThan": "6.14",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.0.*",
              "status": "unaffected",
              "version": "7.0.11",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.1",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.0.11",
                  "versionStartIncluding": "6.14",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.1",
                  "versionStartIncluding": "6.14",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nafs: Fix the locking used by afs_get_link()\n\nThe afs filesystem in the kernel doesn\u0027t do locking correctly for symbolic\nlinks.  There are a number of problems:\n\n (1) It doesn\u0027t do any locking around afs_read_single() to prevent races\n     between multiple -\u003eget_link() calls, thereby allowing the possibility\n     of leaks.\n\n (2) It doesn\u0027t use RCU barriering when accessing the buffer pointers\n     during RCU pathwalk.\n\n (3) It can race with another thread updating the contents of the symlink\n     if a third party updated it on the server.\n\nFix this by the following means:\n\n (0) Move symlink handling into its own file as this makes it more\n     complicated.\n\n (1) Take the validate_lock around afs_read_single() to prevent races\n     between multiple -\u003eget_link() calls.\n\n (2) Keep a separate copy of the symlink contents with an rcu_head.  This\n     is always going to be a lot smaller than a page, so it can be\n     kmalloc\u0027d and save quite a bit of memory.  It also needs a refcount\n     for non-RCU pathwalk.\n\n (3) Split the symlink read and write-to-cache routines in afs from those\n     for directories.\n\n (4) Discard the I/O buffer as soon as the write-to-cache completes as this\n     is a full page (plus a folio_queue).\n\n (5) If there\u0027s no cache, discard the I/O buffer immediately after reading\n     and copying if there is no cache."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.8,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - The flaw is in the AFS client VFS `-\u003eget_link` handler reached only via local syscalls (path resolution, `readlink`, and AFS automount), not from in-kernel network protocol handlers processing remote packets.\nAC:L - An attacker can reliably trigger the races by spawning concurrent `open`/`readlink`/pathwalk threads against the same AFS symlink, and can also drive server-side invalidation if they have AFS write access to that symlink.\nPR:L - Exploitation requires only normal filesystem access to traverse or read AFS symlinks on an already-mounted volume; it does not require real init-namespace root, only the same permissions any unprivileged AFS user would have.\nUI:N - No victim interaction is required beyond the attacker issuing their own concurrent symlink-access syscalls on paths they can already reach.\nS:U - Impact is confined to kernel memory corruption or disclosure on the AFS client host; it does not cross VM, container, or IOMMU security boundaries.\nC:H - Missing RCU protection and absent locking around symlink buffer access allow concurrent invalidation/reallocation to expose stale or freed folio memory during RCU pathwalk and concurrent `afs_read_single()` calls.\nI:H - The unsynchronized buffer races constitute use-after-free class corruption that can be leveraged for heap manipulation and arbitrary kernel writes, not merely a bounded symlink read error.\nA:H - Use-after-free and concurrent invalidation of symlink folio buffers during active `get_link`/`readlink` operations can cause kernel oopses or panics, and the races are repeatable on demand."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-05T12:38:46.858Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/77ea917cbed62882a33114b1e23ededb977e4287"
        },
        {
          "url": "https://git.kernel.org/stable/c/c0410adf3da6db46f3513411fcf95e63c2f1d1ad"
        }
      ],
      "title": "afs: Fix the locking used by afs_get_link()",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-64057",
    "datePublished": "2026-07-19T15:39:38.321Z",
    "dateReserved": "2026-07-19T07:54:57.030Z",
    "dateUpdated": "2026-08-05T12:38:46.858Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2026-64057",
      "date": "2026-08-11",
      "epss": "0.0012",
      "percentile": "0.02169"
    },
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-64057\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2026-07-19T16:17:46.187\",\"lastModified\":\"2026-07-30T14:59:47.950\",\"vulnStatus\":\"Awaiting Analysis\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"In the Linux kernel, the following vulnerability has been resolved:\\n\\nafs: Fix the locking used by afs_get_link()\\n\\nThe afs filesystem in the kernel doesn\u0027t do locking correctly for symbolic\\nlinks.  There are a number of problems:\\n\\n (1) It doesn\u0027t do any locking around afs_read_single() to prevent races\\n     between multiple -\u003eget_link() calls, thereby allowing the possibility\\n     of leaks.\\n\\n (2) It doesn\u0027t use RCU barriering when accessing the buffer pointers\\n     during RCU pathwalk.\\n\\n (3) It can race with another thread updating the contents of the symlink\\n     if a third party updated it on the server.\\n\\nFix this by the following means:\\n\\n (0) Move symlink handling into its own file as this makes it more\\n     complicated.\\n\\n (1) Take the validate_lock around afs_read_single() to prevent races\\n     between multiple -\u003eget_link() calls.\\n\\n (2) Keep a separate copy of the symlink contents with an rcu_head.  This\\n     is always going to be a lot smaller than a page, so it can be\\n     kmalloc\u0027d and save quite a bit of memory.  It also needs a refcount\\n     for non-RCU pathwalk.\\n\\n (3) Split the symlink read and write-to-cache routines in afs from those\\n     for directories.\\n\\n (4) Discard the I/O buffer as soon as the write-to-cache completes as this\\n     is a full page (plus a folio_queue).\\n\\n (5) If there\u0027s no cache, discard the I/O buffer immediately after reading\\n     and copying if there is no cache.\"}],\"affected\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"affectedData\":[{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"unaffected\",\"programFiles\":[\"fs/afs/Makefile\",\"fs/afs/dir.c\",\"fs/afs/fsclient.c\",\"fs/afs/inode.c\",\"fs/afs/internal.h\",\"fs/afs/symlink.c\",\"fs/afs/validation.c\",\"fs/afs/yfsclient.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"eae9e78951bb02a7b94a9adef6e981413d13c564\",\"lessThan\":\"77ea917cbed62882a33114b1e23ededb977e4287\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"eae9e78951bb02a7b94a9adef6e981413d13c564\",\"lessThan\":\"c0410adf3da6db46f3513411fcf95e63c2f1d1ad\",\"versionType\":\"git\",\"status\":\"affected\"}]},{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"affected\",\"programFiles\":[\"fs/afs/Makefile\",\"fs/afs/dir.c\",\"fs/afs/fsclient.c\",\"fs/afs/inode.c\",\"fs/afs/internal.h\",\"fs/afs/symlink.c\",\"fs/afs/validation.c\",\"fs/afs/yfsclient.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"6.14\",\"status\":\"affected\"},{\"version\":\"0\",\"lessThan\":\"6.14\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.0.11\",\"lessThanOrEqual\":\"7.0.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.1\",\"lessThanOrEqual\":\"*\",\"versionType\":\"original_commit_for_fix\",\"status\":\"unaffected\"}]}]}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H\",\"baseScore\":7.8,\"baseSeverity\":\"HIGH\",\"attackVector\":\"LOCAL\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"LOW\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"HIGH\",\"integrityImpact\":\"HIGH\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":1.8,\"impactScore\":5.9}]},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/77ea917cbed62882a33114b1e23ededb977e4287\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/c0410adf3da6db46f3513411fcf95e63c2f1d1ad\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}",
    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-07-20T17:08:46+00:00",
      "cve": "CVE-2026-64057",
      "id": "CVE-2026-64057",
      "initial_release_date": "2026-07-19T00:00:00+00:00",
      "product_status:known_affected": "76",
      "product_status:known_not_affected": "198",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: afs: Fix the locking used by afs_get_link()",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-64057.json",
      "version": "3"
    },
    "suse_vex": {
      "aggregate_severity": "important",
      "current_release_date": "2026-08-05T00:34:08Z",
      "cve": "CVE-2026-64057",
      "id": "CVE-2026-64057",
      "initial_release_date": "2026-07-21T13:00:27Z",
      "product_status:known_not_affected": "298",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-64057",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-64057.json",
      "version": "3"
    }
  }
}



Log in or create an account to share your comment.




Tags
Taxonomy of the tags.





Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

Author Source Type Date Other

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.