netfilter: nf_tables: fix inverted genmask check in nft_map_catchall_activate()

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Summary

CVECVE-2026-23111
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-02-13 14:16:10 UTC
Updated2026-04-03 14:16:23 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: netfilter: nf_tables: fix inverted genmask check in nft_map_catchall_activate() nft_map_catchall_activate() has an inverted element activity check compared to its non-catchall counterpart nft_mapelem_activate() and compared to what is logically required. nft_map_catchall_activate() is called from the abort path to re-activate catchall map elements that were deactivated during a failed transaction. It should skip elements that are already active (they don't need re-activation) and process elements that are inactive (they need to be restored). Instead, the current code does the opposite: it skips inactive elements and processes active ones. Compare the non-catchall activate callback, which is correct: nft_mapelem_activate(): if (nft_set_elem_active(ext, iter->genmask)) return 0; /* skip active, process inactive */ With the buggy catchall version: nft_map_catchall_activate(): if (!nft_set_elem_active(ext, genmask)) continue; /* skip inactive, process active */ The consequence is that when a DELSET operation is aborted, nft_setelem_data_activate() is never called for the catchall element. For NFT_GOTO verdict elements, this means nft_data_hold() is never called to restore the chain->use reference count. Each abort cycle permanently decrements chain->use. Once chain->use reaches zero, DELCHAIN succeeds and frees the chain while catchall verdict elements still reference it, resulting in a use-after-free. This is exploitable for local privilege escalation from an unprivileged user via user namespaces + nftables on distributions that enable CONFIG_USER_NS and CONFIG_NF_TABLES. Fix by removing the negation so the check matches nft_mapelem_activate(): skip active elements, process inactive ones.

Risk And Classification

Primary CVSS: v3.1 7.8 HIGH from [email protected]

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

Problem Types: CWE-416

VersionSourceTypeScoreSeverityVector
3.1[email protected]Primary7.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
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

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Operating System Linux Linux Kernel All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 25aa2ad37c2162be1c0bc4fe6397f7e4c13f00f8 8c760ba4e36c750379d13569f23f5a6e185333f5 git Not specified
CNA Linux Linux affected d60be2da67d172aecf866302c91ea11533eca4d9 b9b6573421de51829f7ec1cce76d85f5f6fbbd7f git Not specified
CNA Linux Linux affected 628bd3e49cba1c066228e23d71a852c23e26da73 42c574c1504aa089a0a142e4c13859327570473d git Not specified
CNA Linux Linux affected 628bd3e49cba1c066228e23d71a852c23e26da73 1444ff890b4653add12f734ffeffc173d42862dd git Not specified
CNA Linux Linux affected 628bd3e49cba1c066228e23d71a852c23e26da73 8b68a45f9722f2babe9e7bad00aa74638addf081 git Not specified
CNA Linux Linux affected 628bd3e49cba1c066228e23d71a852c23e26da73 f41c5d151078c5348271ffaf8e7410d96f2d82f8 git Not specified
CNA Linux Linux affected bc9f791d2593f17e39f87c6e2b3a36549a3705b1 git Not specified
CNA Linux Linux affected 3c7ec098e3b588434a8b07ea9b5b36f04cef1f50 git Not specified
CNA Linux Linux affected a136b7942ad2a50de708f76ea299ccb45ac7a7f9 git Not specified
CNA Linux Linux affected dc7cdf8cbcbf8b13de1df93f356ec04cdeef5c41 git Not specified
CNA Linux Linux affected 6.4 Not specified
CNA Linux Linux unaffected 6.4 semver Not specified
CNA Linux Linux unaffected 5.15.200 5.15.* semver Not specified
CNA Linux Linux unaffected 6.1.163 6.1.* semver Not specified
CNA Linux Linux unaffected 6.6.124 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.70 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.10 6.18.* semver Not specified
CNA Linux Linux unaffected 6.19 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/8b68a45f9722f2babe9e7bad00aa74638addf081 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/42c574c1504aa089a0a142e4c13859327570473d 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/b9b6573421de51829f7ec1cce76d85f5f6fbbd7f 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/1444ff890b4653add12f734ffeffc173d42862dd 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/f41c5d151078c5348271ffaf8e7410d96f2d82f8 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/8c760ba4e36c750379d13569f23f5a6e185333f5 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
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