{"id":"AZL-82697","summary":"CVE-2026-31424 affecting package kernel for versions less than 6.6.134.1-2","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: x_tables: restrict xt_check_match/xt_check_target extensions for NFPROTO_ARP\n\nWeiming Shi says:\n\nxt_match and xt_target structs registered with NFPROTO_UNSPEC can be\nloaded by any protocol family through nft_compat. When such a\nmatch/target sets .hooks to restrict which hooks it may run on, the\nbitmask uses NF_INET_* constants. This is only correct for families\nwhose hook layout matches NF_INET_*: IPv4, IPv6, INET, and bridge\nall share the same five hooks (PRE_ROUTING ... POST_ROUTING).\n\nARP only has three hooks (IN=0, OUT=1, FORWARD=2) with different\nsemantics. Because NF_ARP_OUT == 1 == NF_INET_LOCAL_IN, the .hooks\nvalidation silently passes for the wrong reasons, allowing matches to\nrun on ARP chains where the hook assumptions (e.g. state-\u003ein being\nset on input hooks) do not hold. This leads to NULL pointer\ndereferences; xt_devgroup is one concrete example:\n\n Oops: general protection fault, probably for non-canonical address 0xdffffc0000000044: 0000 [#1] SMP KASAN NOPTI\n KASAN: null-ptr-deref in range [0x0000000000000220-0x0000000000000227]\n RIP: 0010:devgroup_mt+0xff/0x350\n Call Trace:\n  \u003cTASK\u003e\n  nft_match_eval (net/netfilter/nft_compat.c:407)\n  nft_do_chain (net/netfilter/nf_tables_core.c:285)\n  nft_do_chain_arp (net/netfilter/nft_chain_filter.c:61)\n  nf_hook_slow (net/netfilter/core.c:623)\n  arp_xmit (net/ipv4/arp.c:666)\n  \u003c/TASK\u003e\n Kernel panic - not syncing: Fatal exception in interrupt\n\nFix it by restricting arptables to NFPROTO_ARP extensions only.\nNote that arptables-legacy only supports:\n\n- arpt_CLASSIFY\n- arpt_mangle\n- arpt_MARK\n\nthat provide explicit NFPROTO_ARP match/target declarations.","modified":"2026-08-28T17:47:55.665335064Z","published":"2026-04-13T14:16:12Z","upstream":["CVE-2026-31424"],"references":[{"type":"WEB","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-31424"}],"affected":[{"package":{"name":"kernel","ecosystem":"Azure Linux:3","purl":"pkg:rpm/azure-linux/kernel"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.6.134.1-2"}]}],"database_specific":{"source":"https://github.com/microsoft/AzureLinuxVulnerabilityData/blob/main/osv/AZL-82697.json"}}],"schema_version":"1.9.0"}