netfilter: nft_set_pipapo: split gc into unlink and reclaim phase

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Summary

CVECVE-2026-23351
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-03-25 11:16:33 UTC
Updated2026-04-02 15:16:31 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: netfilter: nft_set_pipapo: split gc into unlink and reclaim phase Yiming Qian reports Use-after-free in the pipapo set type: Under a large number of expired elements, commit-time GC can run for a very long time in a non-preemptible context, triggering soft lockup warnings and RCU stall reports (local denial of service). We must split GC in an unlink and a reclaim phase. We cannot queue elements for freeing until pointers have been swapped. Expired elements are still exposed to both the packet path and userspace dumpers via the live copy of the data structure. call_rcu() does not protect us: dump operations or element lookups starting after call_rcu has fired can still observe the free'd element, unless the commit phase has made enough progress to swap the clone and live pointers before any new reader has picked up the old version. This a similar approach as done recently for the rbtree backend in commit 35f83a75529a ("netfilter: nft_set_rbtree: don't gc elements on insert").

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: 0.000390000 probability, percentile 0.120770000 (date 2026-04-02)

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 3c4287f62044a90e73a561aa05fc46e62da173da 16f3595c0441d87dfa005c47d8f95be213afaa9e git Not specified
CNA Linux Linux affected 3c4287f62044a90e73a561aa05fc46e62da173da 7864c667aed01a58b87ca518a631322cd0ac34c0 git Not specified
CNA Linux Linux affected 3c4287f62044a90e73a561aa05fc46e62da173da c12d570d71920903a1a0468b7d13b085203d0c93 git Not specified
CNA Linux Linux affected 3c4287f62044a90e73a561aa05fc46e62da173da 500a50a301ce962b019ab95053ac70264fec2c21 git Not specified
CNA Linux Linux affected 3c4287f62044a90e73a561aa05fc46e62da173da aff13667708dfa0dce136b8efd81baa9fa6ef261 git Not specified
CNA Linux Linux affected 3c4287f62044a90e73a561aa05fc46e62da173da 9df95785d3d8302f7c066050117b04cd3c2048c2 git Not specified
CNA Linux Linux affected 5.6 Not specified
CNA Linux Linux unaffected 5.6 semver Not specified
CNA Linux Linux unaffected 6.1.167 6.1.* semver Not specified
CNA Linux Linux unaffected 6.6.130 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.77 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.17 6.18.* semver Not specified
CNA Linux Linux unaffected 6.19.7 6.19.* semver Not specified
CNA Linux Linux unaffected 7.0-rc3 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/aff13667708dfa0dce136b8efd81baa9fa6ef261 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/7864c667aed01a58b87ca518a631322cd0ac34c0 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/9df95785d3d8302f7c066050117b04cd3c2048c2 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/16f3595c0441d87dfa005c47d8f95be213afaa9e 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/500a50a301ce962b019ab95053ac70264fec2c21 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/c12d570d71920903a1a0468b7d13b085203d0c93 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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