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CVE-2026-31424

netfilter: x_tables: restrict xt_check_match/xt_check_target extensions for NFPROTO_ARP

Published
Last modified
published
Not listed in CISA KEV
Fix
Fixed in 5.10.253, 5.15.203, 6.1.168, 6.6.134, 6.12.81, and 2 more
None on Exploit-DB, Metasploit or GitHub

Summary

In the Linux kernel, the following vulnerability has been resolved: netfilter: x_tables: restrict xt_check_match/xt_check_target extensions for NFPROTO_ARP Weiming Shi says: xt_match and xt_target structs registered with NFPROTO_UNSPEC can be loaded by any protocol family through nft_compat. When such a match/target sets .hooks to restrict which hooks it may run on, the bitmask uses NF_INET_* constants. This is only correct for families whose hook layout matches NF_INET_*: IPv4, IPv6, INET, and bridge all share the same five hooks (PRE_ROUTING ... POST_ROUTING). ARP only has three hooks (IN=0, OUT=1, FORWARD=2) with different semantics. Because NF_ARP_OUT == 1 == NF_INET_LOCAL_IN, the .hooks validation silently passes for the wrong reasons, allowing matches to run on ARP chains where the hook assumptions (e.g. state->in being set on input hooks) do not hold. This leads to NULL pointer dereferences; xt_devgroup is one concrete example: Oops: general protection fault, probably for non-canonical address 0xdffffc0000000044: 0000 [#1] SMP KASAN NOPTI KASAN: null-ptr-deref in range [0x0000000000000220-0x0000000000000227] RIP: 0010:devgroup_mt+0xff/0x350 Call Trace: <TASK> nft_match_eval (net/netfilter/nft_compat.c:407) nft_do_chain (net/netfilter/nf_tables_core.c:285) nft_do_chain_arp (net/netfilter/nft_chain_filter.c:61) nf_hook_slow (net/netfilter/core.c:623) arp_xmit (net/ipv4/arp.c:666) </TASK> Kernel panic - not syncing: Fatal exception in interrupt Fix it by restricting arptables to NFPROTO_ARP extensions only. Note that arptables-legacy only supports: • arpt_CLASSIFY • arpt_mangle • arpt_MARK that provide explicit NFPROTO_ARP match/target declarations.

Timeline

  1. CVE published
  2. Record last updated

Affected versions

  • Linux Linux

    From 9291747f118d6404e509747b85ff5f6dfec368d2 · fixed in 80e3c75f71c3ea1e62fcb032382de13e00a68f8b; From 9291747f118d6404e509747b85ff5f6dfec368d2 · fixed in d9a0af9e43416aa50c0595e15fa01365a1c72c49; From 9291747f118d6404e509747b85ff5f6dfec368d2 · fixed in 1cd6313c8644bfebbd813a05da9daa21b09dd68c; From 9291747f118d6404e509747b85ff5f6dfec368d2 · fixed in f00ac65c90ea475719e08d629e2e26c8b4e6999b; From 9291747f118d6404e509747b85ff5f6dfec368d2 · fixed in e7e1b6bcb389c8708003d40613a59ff2496f6b1f; From 9291747f118d6404e509747b85ff5f6dfec368d2 · fixed in dc3e27dd7d76e21106b8f9bbdc31f5da74a89014; From 9291747f118d6404e509747b85ff5f6dfec368d2 · fixed in 3e79374b03bf9a2f282f0eb1d0ac3776f7e0f28a; From 9291747f118d6404e509747b85ff5f6dfec368d2 · fixed in 3d5d488f11776738deab9da336038add95d342d1

  • Linux Linux

    2.6.39

  • KernelLinux

    From 2.6.39 · fixed in 5.10.253; From 5.11.0 · fixed in 5.15.203; From 5.16.0 · fixed in 6.1.168; From 6.2.0 · fixed in 6.6.134; From 6.7.0 · fixed in 6.12.81; From 6.13.0 · fixed in 6.18.22; From 6.19.0 · fixed in 6.19.12

References 8

git.kernel.org