CVE-2026-23351 (GCVE-0-2026-23351)

Vulnerability from cvelistv5 – Published: 2026-03-25 10:27 – Updated: 2026-03-25 10:27
VLAI?
Title
netfilter: nft_set_pipapo: split gc into unlink and reclaim phase
Summary
In 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").
Severity ?
No CVSS data available.
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: 3c4287f62044a90e73a561aa05fc46e62da173da , < 16f3595c0441d87dfa005c47d8f95be213afaa9e (git)
Affected: 3c4287f62044a90e73a561aa05fc46e62da173da , < 7864c667aed01a58b87ca518a631322cd0ac34c0 (git)
Affected: 3c4287f62044a90e73a561aa05fc46e62da173da , < c12d570d71920903a1a0468b7d13b085203d0c93 (git)
Affected: 3c4287f62044a90e73a561aa05fc46e62da173da , < 500a50a301ce962b019ab95053ac70264fec2c21 (git)
Affected: 3c4287f62044a90e73a561aa05fc46e62da173da , < aff13667708dfa0dce136b8efd81baa9fa6ef261 (git)
Affected: 3c4287f62044a90e73a561aa05fc46e62da173da , < 9df95785d3d8302f7c066050117b04cd3c2048c2 (git)
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    Linux Linux Affected: 5.6
Unaffected: 0 , < 5.6 (semver)
Unaffected: 6.1.167 , ≤ 6.1.* (semver)
Unaffected: 6.6.130 , ≤ 6.6.* (semver)
Unaffected: 6.12.77 , ≤ 6.12.* (semver)
Unaffected: 6.18.17 , ≤ 6.18.* (semver)
Unaffected: 6.19.7 , ≤ 6.19.* (semver)
Unaffected: 7.0-rc3 , ≤ * (original_commit_for_fix)
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          "programFiles": [
            "include/net/netfilter/nf_tables.h",
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            "net/netfilter/nft_set_pipapo.h"
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: nft_set_pipapo: split gc into unlink and reclaim phase\n\nYiming Qian reports Use-after-free in the pipapo set type:\n  Under a large number of expired elements, commit-time GC can run for a very\n  long time in a non-preemptible context, triggering soft lockup warnings and\n  RCU stall reports (local denial of service).\n\nWe must split GC in an unlink and a reclaim phase.\n\nWe cannot queue elements for freeing until pointers have been swapped.\nExpired elements are still exposed to both the packet path and userspace\ndumpers via the live copy of the data structure.\n\ncall_rcu() does not protect us: dump operations or element lookups starting\nafter call_rcu has fired can still observe the free\u0027d element, unless the\ncommit phase has made enough progress to swap the clone and live pointers\nbefore any new reader has picked up the old version.\n\nThis a similar approach as done recently for the rbtree backend in commit\n35f83a75529a (\"netfilter: nft_set_rbtree: don\u0027t gc elements on insert\")."
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    "dateReserved": "2026-01-13T15:37:45.999Z",
    "dateUpdated": "2026-03-25T10:27:36.854Z",
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}


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  • 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.
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