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CVE PROGRAM SOURCE RECORD7.8 High

CVE-2026-23111

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

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Status
Published
Published
Updated
Assigning organization
Linux

Description

In 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.

Affected products

Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.

Linux Linux

Default version status: unaffected

  • 25aa2ad37c2162be1c0bc4fe6397f7e4c13f00f8 to < 8c760ba4e36c750379d13569f23f5a6e185333f5affected
  • d60be2da67d172aecf866302c91ea11533eca4d9 to < b9b6573421de51829f7ec1cce76d85f5f6fbbd7faffected
  • 628bd3e49cba1c066228e23d71a852c23e26da73 to < 42c574c1504aa089a0a142e4c13859327570473daffected
  • 628bd3e49cba1c066228e23d71a852c23e26da73 to < 1444ff890b4653add12f734ffeffc173d42862ddaffected
  • 628bd3e49cba1c066228e23d71a852c23e26da73 to < 8b68a45f9722f2babe9e7bad00aa74638addf081affected
  • 628bd3e49cba1c066228e23d71a852c23e26da73 to < f41c5d151078c5348271ffaf8e7410d96f2d82f8affected
  • bc9f791d2593f17e39f87c6e2b3a36549a3705b1affected
  • 3c7ec098e3b588434a8b07ea9b5b36f04cef1f50affected
  • a136b7942ad2a50de708f76ea299ccb45ac7a7f9affected
  • dc7cdf8cbcbf8b13de1df93f356ec04cdeef5c41affected
  • 5.15.121 to < 5.15.200affected
  • 6.1.36 to < 6.1.163affected
  • 4.19.316 to < 4.20affected
  • 5.4.262 to < 5.5affected
  • 5.10.188 to < 5.11affected
  • 6.3.10 to < 6.4affected

Linux Linux

Default version status: affected

  • 6.4affected
  • 0 to < 6.4unaffected
  • 5.15.200 to ≤ 5.15.*unaffected
  • 6.1.163 to ≤ 6.1.*unaffected
  • 6.6.124 to ≤ 6.6.*unaffected
  • 6.12.70 to ≤ 6.12.*unaffected
  • 6.18.10 to ≤ 6.18.*unaffected
  • 6.19 to ≤ *unaffected

References