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GHSA-PW4J-JRV7-FQ3M

Vulnerability from github – Published: 2026-09-11 21:31 – Updated: 2026-09-14 15:32

Details

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

smack: fix cred UAF in smack_file_send_sigiotask()

When inspecting the credentials of another task, objective credentials (->real_cred, accessed with __task_cred()) must always be used.

Accessing ->cred on a non-current task is forbidden unless that task is being created or destroyed; a task is allowed to change its own ->cred pointer with no synchronization, and changing ->cred should only affect the current syscall.

smack_file_send_sigiotask() was accessing both sets of credentials: First tsk->cred, then __task_cred(tsk).

Fix it, always access the objective credentials here.

I have tested that this bug can lead to a KASAN-reported UAF of struct cred in smack_file_send_sigiotask(), and that this fix prevents the race.

Severity

7.8 (High)


                  
                    CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

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{
  "affected": [],
  "aliases": [
    "CVE-2026-80928"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-09-11T20:18:56Z",
    "severity": "HIGH"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nsmack: fix cred UAF in smack_file_send_sigiotask()\n\nWhen inspecting the credentials of another task, objective credentials\n(-\u003ereal_cred, accessed with __task_cred()) must always be used.\n\nAccessing -\u003ecred on a non-current task is forbidden unless that task is\nbeing created or destroyed; a task is allowed to change its own -\u003ecred\npointer with no synchronization, and changing -\u003ecred should only affect the\ncurrent syscall.\n\nsmack_file_send_sigiotask() was accessing both sets of credentials: First\ntsk-\u003ecred, then __task_cred(tsk).\n\nFix it, always access the objective credentials here.\n\nI have tested that this bug can lead to a KASAN-reported UAF of struct cred\nin smack_file_send_sigiotask(), and that this fix prevents the race.",
  "id": "GHSA-pw4j-jrv7-fq3m",
  "modified": "2026-09-14T15:32:19Z",
  "published": "2026-09-11T21:31:19Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-80928"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/7c7fe043f3099d0d35002b248967f75e55345b93"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/a512366d84e134a9eefc2cc40eeb6e80e2ec162c"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/b5bcf3adfa27279da4401ab8f1e1a706601a92be"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/b791401bf389a1546a830d2b381ca60fe94c7870"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/ed64aa505875a3b4defd504ee8e59e1949246a62"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/f9c7b1f2b9d8f4176d2632743f51400855978ace"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/fedc88e38ce979a720cd2de042578cb5df3dc8de"
    }
  ],
  "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"
    }
  ]
}

CVE-2026-80928 (GCVE-0-2026-80928)

Vulnerability from cvelistv5 – Published: 2026-09-11 19:42 – Updated: 2026-09-14 11:58

Title

smack: fix cred UAF in smack_file_send_sigiotask()

Summary

In the Linux kernel, the following vulnerability has been resolved: smack: fix cred UAF in smack_file_send_sigiotask() When inspecting the credentials of another task, objective credentials (->real_cred, accessed with __task_cred()) must always be used. Accessing ->cred on a non-current task is forbidden unless that task is being created or destroyed; a task is allowed to change its own ->cred pointer with no synchronization, and changing ->cred should only affect the current syscall. smack_file_send_sigiotask() was accessing both sets of credentials: First tsk->cred, then __task_cred(tsk). Fix it, always access the objective credentials here. I have tested that this bug can lead to a KASAN-reported UAF of struct cred in smack_file_send_sigiotask(), and that this fix prevents the race.

Severity

7.8 (High)


                        
                          CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Assigner

Linux mitre root

References

7 references

URL	Tags
https://git.kernel.org/stable/c/a512366d84e134a9e…
https://git.kernel.org/stable/c/7c7fe043f3099d0d3…
https://git.kernel.org/stable/c/f9c7b1f2b9d8f4176…
https://git.kernel.org/stable/c/b5bcf3adfa27279da…
https://git.kernel.org/stable/c/ed64aa505875a3b4d…
https://git.kernel.org/stable/c/b791401bf389a1546…
https://git.kernel.org/stable/c/fedc88e38ce979a72…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: 3b11a1decef07c19443d24ae926982bc8ec9f4c0 , < a512366d84e134a9eefc2cc40eeb6e80e2ec162c (git) Affected: 3b11a1decef07c19443d24ae926982bc8ec9f4c0 , < 7c7fe043f3099d0d35002b248967f75e55345b93 (git) Affected: 3b11a1decef07c19443d24ae926982bc8ec9f4c0 , < f9c7b1f2b9d8f4176d2632743f51400855978ace (git) Affected: 3b11a1decef07c19443d24ae926982bc8ec9f4c0 , < b5bcf3adfa27279da4401ab8f1e1a706601a92be (git) Affected: 3b11a1decef07c19443d24ae926982bc8ec9f4c0 , < ed64aa505875a3b4defd504ee8e59e1949246a62 (git) Affected: 3b11a1decef07c19443d24ae926982bc8ec9f4c0 , < b791401bf389a1546a830d2b381ca60fe94c7870 (git) Affected: 3b11a1decef07c19443d24ae926982bc8ec9f4c0 , < fedc88e38ce979a720cd2de042578cb5df3dc8de (git)
Linux	Linux	Affected: 2.6.29 Unaffected: 0 , < 2.6.29 (semver) Unaffected: 5.15.221 , ≤ 5.15.* (semver) Unaffected: 6.1.188 , ≤ 6.1.* (semver) Unaffected: 6.6.157 , ≤ 6.6.* (semver) Unaffected: 6.12.109 , ≤ 6.12.* (semver) Unaffected: 6.18.50 , ≤ 6.18.* (semver) Unaffected: 7.2.4 , ≤ 7.2.* (semver) Unaffected: 7.3-rc1 , ≤ * (original_commit_for_fix)

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              "versionType": "semver"
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            {
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsmack: fix cred UAF in smack_file_send_sigiotask()\n\nWhen inspecting the credentials of another task, objective credentials\n(-\u003ereal_cred, accessed with __task_cred()) must always be used.\n\nAccessing -\u003ecred on a non-current task is forbidden unless that task is\nbeing created or destroyed; a task is allowed to change its own -\u003ecred\npointer with no synchronization, and changing -\u003ecred should only affect the\ncurrent syscall.\n\nsmack_file_send_sigiotask() was accessing both sets of credentials: First\ntsk-\u003ecred, then __task_cred(tsk).\n\nFix it, always access the objective credentials here.\n\nI have tested that this bug can lead to a KASAN-reported UAF of struct cred\nin smack_file_send_sigiotask(), and that this fix prevents the race."
        }
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            "version": "3.1"
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              "value": "AV:L - Reachable only via local syscalls: fcntl(F_SETOWN)/O_ASYNC on a pipe or socket, then write or MSG_OOB so kill_fasync()/send_sigurg() call smack_file_send_sigiotask(). Same SIGIO path as CVE-2026-72183 (AV:L); a remote peer can raise SIGIO only on a socket the local attacker already owns.\nAC:L - The attacker controls both sides of the race: one thread loops faccessat() so access_override_creds() installs a non_rcu subjective cred that revert_creds()+put_cred() frees without RCU, while another thread writes the pipe or sends OOB to fire SIGIO. The fix author reproduced a KASAN cred UAF; the window is retryable.\nPR:L - pipe(), fcntl(F_SETOWN/F_SETFL), write(), and faccessat() need no capabilities. An unprivileged user namespace (unshare(CLONE_NEWUSER)) makes access() install the non_rcu override (non-root uid with caps, or real uid != fsuid). The UAF is kernel cred memory on the attacker\u2019s own task.\nUI:N - No victim action is required. The attacker arms fowner on their own file, overrides their own subjective creds via faccessat(), and triggers SIGIO themselves.\nS:U - This is in-kernel cred use-after-free leading to local privilege escalation within the kernel security authority. It is not a VM escape, IOMMU bypass, or userspace sandbox boundary crossing.\nC:H - This is a use-after-free of struct cred. After free, the cred slab can be sprayed so cred-\u003esecurity and the derived smack_known are attacker-controlled, enabling arbitrary kernel reads through smk_access() and smack_log(). Kernel UAF scores C:H.\nI:H - The same sprayed cred/task_smack/smack_known objects yield a fake-object primitive on the SIGIO path, exploitable for control-flow hijacking and arbitrary write as with other kernel cred UAFs. Kernel UAF scores I:H.\nA:H - The fix author confirmed a KASAN use-after-free of struct cred in smack_file_send_sigiotask(). Dereferencing the freed cred on the SIGIO path, including from kill_fasync() in interrupt context, causes a kernel oops or panic."
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          "url": "https://git.kernel.org/stable/c/fedc88e38ce979a720cd2de042578cb5df3dc8de"
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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.

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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GHSA-PW4J-JRV7-FQ3M

CVE-2026-80928 (GCVE-0-2026-80928)

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