VulnerabilityPublished 13 Apr 2026Updated 5 Nov 2026

CVE-2026-31424: Linux kernel · netfilter: x_tables: restrict xt_check_match/xt_check_target extensions for NFPROTO_ARP

Affects Linux kernelSource CVE Database V5

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Not known to be exploited · fixed in f00ac65c90ea475719e08d629e2e26c8b4e6999b : update Linux kernel when convenient.

Data as of 5 Nov 2026, 22:04 UTC

Severity

Unrated

Rated by Threat Radar · No CVSS score from NVD or the CNA

Thin evidence

One scorer or none

Exploitation: No evidence of active exploitation and no public proof of concept
Automatable: Attackers cannot reliably automate steps 1–4 of the kill chain
Technical impact: Limited control over the software or limited information exposure

CISA SSVC assessment, 2026-11-05.

Patch

Available – fixed in f00ac65c90ea475719e08d629e2e26c8b4e6999b, e7e1b6bcb389c8708003d40613a59ff2496f6b1f, dc3e27dd7d76e21106b8f9bbdc31f5da74a89014 +5

Exploitation evidence

Disclosed: evidence found.
CVE published 13 Apr 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 5 Nov 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ 9291747f118d6404e509747b85ff5f6dfec368d2, < f00ac65c90ea475719e08d629e2e26c8b4e6999b	Fixed in f00ac65c90ea475719e08d629e2e26c8b4e6999b
LinuxLinux	Affected ≥ 9291747f118d6404e509747b85ff5f6dfec368d2, < e7e1b6bcb389c8708003d40613a59ff2496f6b1f	Fixed in e7e1b6bcb389c8708003d40613a59ff2496f6b1f
LinuxLinux	Affected ≥ 9291747f118d6404e509747b85ff5f6dfec368d2, < dc3e27dd7d76e21106b8f9bbdc31f5da74a89014	Fixed in dc3e27dd7d76e21106b8f9bbdc31f5da74a89014
LinuxLinux	Affected ≥ 9291747f118d6404e509747b85ff5f6dfec368d2, < d9a0af9e43416aa50c0595e15fa01365a1c72c49	Fixed in d9a0af9e43416aa50c0595e15fa01365a1c72c49
LinuxLinux	Affected ≥ 9291747f118d6404e509747b85ff5f6dfec368d2, < 80e3c75f71c3ea1e62fcb032382de13e00a68f8b	Fixed in 80e3c75f71c3ea1e62fcb032382de13e00a68f8b
LinuxLinux	Affected ≥ 9291747f118d6404e509747b85ff5f6dfec368d2, < 3e79374b03bf9a2f282f0eb1d0ac3776f7e0f28a	Fixed in 3e79374b03bf9a2f282f0eb1d0ac3776f7e0f28a

Description

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.

References

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