pipe: preserve existing fasync readers on writer setup failure

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-99203
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-10-28 11:17:41 UTC
Updated2026-10-31 13:17:59 UTC
DescriptionIn 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.

Risk And Classification

Primary CVSS: v3.1 7.8 HIGH from 416baaa9-dc9f-4396-8d5f-8c081fb06d67

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

EPSS: 0.001710000 probability, percentile 0.064400000 (date 2026-10-31)

VersionSourceTypeScoreSeverityVector
3.1416baaa9-dc9f-4396-8d5f-8c081fb06d67Secondary7.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
3.1CNADECLARED7.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CVSS v3.1 Breakdown

Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

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

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 76398425bb06b07cc3a3b1ce169c67dc9d6874ed 6041bcd185d4df051490fe166e64feae6c3b8291 git Not specified
CNA Linux Linux affected 76398425bb06b07cc3a3b1ce169c67dc9d6874ed 7cdbfa22a7e270b155ddb958b1583a999c0c8abb git Not specified
CNA Linux Linux affected 76398425bb06b07cc3a3b1ce169c67dc9d6874ed 22c7f57b0c0b0b8e19cfb41a1bd85f55715ad386 git Not specified
CNA Linux Linux affected 76398425bb06b07cc3a3b1ce169c67dc9d6874ed 94be790dd6fbe0912f35bb711bea8ef3687eaca9 git Not specified
CNA Linux Linux affected 76398425bb06b07cc3a3b1ce169c67dc9d6874ed 9b0aa2a1d8df51f3dcb363c3a2d9531098e88dc6 git Not specified
CNA Linux Linux affected 76398425bb06b07cc3a3b1ce169c67dc9d6874ed 4c42ce499ce4b1c787e61082e3b13df4f30c4eaa git Not specified
CNA Linux Linux affected 76398425bb06b07cc3a3b1ce169c67dc9d6874ed 2259809e5b7043c4ba20af7b14ba3e471cf55521 git Not specified
CNA Linux Linux affected 76398425bb06b07cc3a3b1ce169c67dc9d6874ed 40bb03d3ea6f6a915218508819ecc4d7a7fa260d git Not specified
CNA Linux Linux affected 2.6.30 Not specified
CNA Linux Linux unaffected 2.6.30 semver Not specified
CNA Linux Linux unaffected 5.10.273 5.10.* semver Not specified
CNA Linux Linux unaffected 5.15.224 5.15.* semver Not specified
CNA Linux Linux unaffected 6.1.191 6.1.* semver Not specified
CNA Linux Linux unaffected 6.6.161 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.115 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.59 6.18.* semver Not specified
CNA Linux Linux unaffected 7.2.13 7.2.* semver Not specified
CNA Linux Linux unaffected 7.3 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/2259809e5b7043c4ba20af7b14ba3e471cf55521 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/6041bcd185d4df051490fe166e64feae6c3b8291 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/7cdbfa22a7e270b155ddb958b1583a999c0c8abb 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/9b0aa2a1d8df51f3dcb363c3a2d9531098e88dc6 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/94be790dd6fbe0912f35bb711bea8ef3687eaca9 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/4c42ce499ce4b1c787e61082e3b13df4f30c4eaa 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/40bb03d3ea6f6a915218508819ecc4d7a7fa260d 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/22c7f57b0c0b0b8e19cfb41a1bd85f55715ad386 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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