Vulnerability-Lookup

GHSA-7F3V-362V-5M4G

Vulnerability from github – Published: 2026-09-11 21:31 – Updated: 2026-09-11 21:31

Details

In the Linux kernel, the following vulnerability has been resolved:

pidfd: hold exec_update_lock around namespace ioctl

The PIDFD_GET_*_NAMESPACE ioctls in pidfd_ioctl() perform a filesystem credentials ptrace access check before handing out a namespace file descriptor. The accompanying comment states that the code "mirrors nsfs behavior", but, unlike the corresponding procfs paths, it does so without holding the target task's exec_update_lock.

proc_ns_get_link() and proc_ns_readlink() both take exec_update_lock for reading around the ptrace check and the namespace lookup, so that the credentials used for the access decision match those of the task when its namespace is read. Without it, a caller can pass the check against the target's old credentials and then read the namespace after the target has execve()'d a setuid binary and committed new credentials -- accessing namespace information it should have been denied.

Hold exec_update_lock for reading around the ptrace check and the namespace lookup so that pidfd truly mirrors nsfs behavior, as the comment already claims. open_namespace() itself runs outside the lock: once a namespace reference is obtained it carries its own refcount and is opened with the caller's own credentials, so a concurrent execve() on the target can no longer affect the outcome.

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{
  "affected": [],
  "aliases": [
    "CVE-2026-89766"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-09-11T20:20:07Z",
    "severity": null
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\npidfd: hold exec_update_lock around namespace ioctl\n\nThe PIDFD_GET_*_NAMESPACE ioctls in pidfd_ioctl() perform a filesystem\ncredentials ptrace access check before handing out a namespace file\ndescriptor.  The accompanying comment states that the code \"mirrors nsfs\nbehavior\", but, unlike the corresponding procfs paths, it does so without\nholding the target task\u0027s exec_update_lock.\n\nproc_ns_get_link() and proc_ns_readlink() both take exec_update_lock for\nreading around the ptrace check and the namespace lookup, so that the\ncredentials used for the access decision match those of the task when its\nnamespace is read.  Without it, a caller can pass the check against the\ntarget\u0027s old credentials and then read the namespace after the target has\nexecve()\u0027d a setuid binary and committed new credentials -- accessing\nnamespace information it should have been denied.\n\nHold exec_update_lock for reading around the ptrace check and the\nnamespace lookup so that pidfd truly mirrors nsfs behavior, as the comment\nalready claims.  open_namespace() itself runs outside the lock: once a\nnamespace reference is obtained it carries its own refcount and is opened\nwith the caller\u0027s own credentials, so a concurrent execve() on the target\ncan no longer affect the outcome.",
  "id": "GHSA-7f3v-362v-5m4g",
  "modified": "2026-09-11T21:31:39Z",
  "published": "2026-09-11T21:31:39Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-89766"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/9688a46802939da28f00cb40e8129615d5d4af39"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/cf24ce48d60225fdbee68ed2058763a1fd172ff3"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/e89318aa8629969e86548b05e7c19283af3f0efb"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}

CVE-2026-89766 (GCVE-0-2026-89766)

Vulnerability from cvelistv5 – Published: 2026-09-11 19:47 – Updated: 2026-09-11 19:47

Title

pidfd: hold exec_update_lock around namespace ioctl

Summary

In the Linux kernel, the following vulnerability has been resolved: pidfd: hold exec_update_lock around namespace ioctl The PIDFD_GET_*_NAMESPACE ioctls in pidfd_ioctl() perform a filesystem credentials ptrace access check before handing out a namespace file descriptor. The accompanying comment states that the code "mirrors nsfs behavior", but, unlike the corresponding procfs paths, it does so without holding the target task's exec_update_lock. proc_ns_get_link() and proc_ns_readlink() both take exec_update_lock for reading around the ptrace check and the namespace lookup, so that the credentials used for the access decision match those of the task when its namespace is read. Without it, a caller can pass the check against the target's old credentials and then read the namespace after the target has execve()'d a setuid binary and committed new credentials -- accessing namespace information it should have been denied. Hold exec_update_lock for reading around the ptrace check and the namespace lookup so that pidfd truly mirrors nsfs behavior, as the comment already claims. open_namespace() itself runs outside the lock: once a namespace reference is obtained it carries its own refcount and is opened with the caller's own credentials, so a concurrent execve() on the target can no longer affect the outcome.

Severity

No CVSS data available.

Assigner

Linux mitre root

References

3 references

URL	Tags
https://git.kernel.org/stable/c/cf24ce48d60225fdb…
https://git.kernel.org/stable/c/e89318aa8629969e8…
https://git.kernel.org/stable/c/9688a46802939da28…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: 5b08bd408534bfb3a7cf5778da5b27d4e4fffe12 , < cf24ce48d60225fdbee68ed2058763a1fd172ff3 (git) Affected: 5b08bd408534bfb3a7cf5778da5b27d4e4fffe12 , < e89318aa8629969e86548b05e7c19283af3f0efb (git) Affected: 5b08bd408534bfb3a7cf5778da5b27d4e4fffe12 , < 9688a46802939da28f00cb40e8129615d5d4af39 (git)
Linux	Linux	Affected: 6.11 Unaffected: 0 , < 6.11 (semver) Unaffected: 6.18.51 , ≤ 6.18.* (semver) Unaffected: 7.2.4 , ≤ 7.2.* (semver) Unaffected: 7.3-rc1 , ≤ * (original_commit_for_fix)

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JSON

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{
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        {
          "defaultStatus": "unaffected",
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          "programFiles": [
            "fs/pidfs.c"
          ],
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          "vendor": "Linux",
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              "status": "affected",
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            }
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              "version": "6.11"
            },
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              "version": "0",
              "versionType": "semver"
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              "status": "unaffected",
              "version": "6.18.51",
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            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.4",
              "versionType": "semver"
            },
            {
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        }
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        }
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    "datePublished": "2026-09-11T19:47:06.597Z",
    "dateReserved": "2026-09-11T19:38:34.764Z",
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}

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.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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