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GHSA-J875-7X9H-G92W

Vulnerability from github – Published: 2026-10-28 12:31 – Updated: 2026-10-28 12:31

Details

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

pipe: preserve existing fasync readers on writer setup failure

F_SETFL and FIOASYNC decide whether to invoke ->fasync() before pipe_fasync() takes pipe->mutex. Two enables of one O_RDWR FIFO can therefore both enter the callback.

fasync_helper() allocates before checking for an existing entry. If the first enable installs both entries, a second enable can update the reader entry and then fail the allocation for the writer entry. The error path removes the pre-existing reader entry, clearing FASYNC while the writer entry remains registered. __fput() then skips ->fasync(), so a later pipe notification can dereference the freed file or its f_owner. An unprivileged memory-pressure reproducer triggers a KASAN slab-use-after-free in send_sigio() through this path.

Keep the reader helper's result and undo the registration only if this call added it. The pipe mutex serializes changes to both lists, so a failed new registration still removes its reader, while a failed duplicate preserves the existing registrations and FASYNC. Successful duplicate enables continue to update fa_fd as before.

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{
  "affected": [],
  "aliases": [
    "CVE-2026-99203"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-10-28T11:17:41Z",
    "severity": null
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\npipe: preserve existing fasync readers on writer setup failure\n\nF_SETFL and FIOASYNC decide whether to invoke -\u003efasync() before\npipe_fasync() takes pipe-\u003emutex. Two enables of one O_RDWR FIFO can\ntherefore both enter the callback.\n\nfasync_helper() allocates before checking for an existing entry. If the\nfirst enable installs both entries, a second enable can update the\nreader entry and then fail the allocation for the writer entry. The\nerror path removes the pre-existing reader entry, clearing FASYNC while\nthe writer entry remains registered. __fput() then skips -\u003efasync(), so a\nlater pipe notification can dereference the freed file or its f_owner.\nAn unprivileged memory-pressure reproducer triggers a KASAN\nslab-use-after-free in send_sigio() through this path.\n\nKeep the reader helper\u0027s result and undo the registration only if this\ncall added it. The pipe mutex serializes changes to both lists, so a\nfailed new registration still removes its reader, while a failed\nduplicate preserves the existing registrations and FASYNC. Successful\nduplicate enables continue to update fa_fd as before.",
  "id": "GHSA-j875-7x9h-g92w",
  "modified": "2026-10-28T12:31:08Z",
  "published": "2026-10-28T12:31:08Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-99203"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/2259809e5b7043c4ba20af7b14ba3e471cf55521"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/40bb03d3ea6f6a915218508819ecc4d7a7fa260d"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/4c42ce499ce4b1c787e61082e3b13df4f30c4eaa"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}

CVE-2026-99203 (GCVE-0-2026-99203)

Vulnerability from cvelistv5 – Published: 2026-10-28 10:35 – Updated: 2026-10-28 10:35

Title

pipe: preserve existing fasync readers on writer setup failure

Summary

In the Linux kernel, the following vulnerability has been resolved: pipe: preserve existing fasync readers on writer setup failure F_SETFL and FIOASYNC decide whether to invoke ->fasync() before pipe_fasync() takes pipe->mutex. Two enables of one O_RDWR FIFO can therefore both enter the callback. fasync_helper() allocates before checking for an existing entry. If the first enable installs both entries, a second enable can update the reader entry and then fail the allocation for the writer entry. The error path removes the pre-existing reader entry, clearing FASYNC while the writer entry remains registered. __fput() then skips ->fasync(), so a later pipe notification can dereference the freed file or its f_owner. An unprivileged memory-pressure reproducer triggers a KASAN slab-use-after-free in send_sigio() through this path. Keep the reader helper's result and undo the registration only if this call added it. The pipe mutex serializes changes to both lists, so a failed new registration still removes its reader, while a failed duplicate preserves the existing registrations and FASYNC. Successful duplicate enables continue to update fa_fd as before.

Severity

No CVSS data available.

Assigner

Linux CNA under the mitre root

CNA scorecard D 53/100 over 7033 records in the last 180 days details

References

3 references

URL	Tags
https://git.kernel.org/stable/c/4c42ce499ce4b1c78…
https://git.kernel.org/stable/c/2259809e5b7043c4b…
https://git.kernel.org/stable/c/40bb03d3ea6f6a915…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: 76398425bb06b07cc3a3b1ce169c67dc9d6874ed , < 4c42ce499ce4b1c787e61082e3b13df4f30c4eaa (git) Affected: 76398425bb06b07cc3a3b1ce169c67dc9d6874ed , < 2259809e5b7043c4ba20af7b14ba3e471cf55521 (git) Affected: 76398425bb06b07cc3a3b1ce169c67dc9d6874ed , < 40bb03d3ea6f6a915218508819ecc4d7a7fa260d (git)
Linux	Linux	Affected: 2.6.30 Unaffected: 0 , < 2.6.30 (semver) Unaffected: 6.18.59 , ≤ 6.18.* (semver) Unaffected: 7.2.13 , ≤ 7.2.* (semver) Unaffected: 7.3 , ≤ * (original_commit_for_fix)

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          "programFiles": [
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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.

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