{"id":"CVE-2026-80837","title":"In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: nf_tables: don't queue packet path object notifications\n\nAll file:line references below are against v7.2-rc4 (ac5b0e5651b1)","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: nf_tables: don't queue packet path object notifications\n\nAll file:line references below are against v7.2-rc4 (ac5b0e5651b1). The\ntrace was captured on 7.2.0-…","severity":"none","vendor":"Linux","product":"Linux","affected":["Linux >= 67cc570edaa02016a8685a06a0ee91f05a6277d9 < 6989f298103f575a768a85e4b19d2384709237f8","Linux >= 67cc570edaa02016a8685a06a0ee91f05a6277d9 < df86c0e84025be8b6dd572a20852698927aa666b","Linux >= 67cc570edaa02016a8685a06a0ee91f05a6277d9 < 6fa88d11983c6fe693c13ed7c5b3b75ae9f39de6","Linux >= 67cc570edaa02016a8685a06a0ee91f05a6277d9 < e97e2d6d0b150fd78be573f9fdf193f204d9334e","Linux >= 67cc570edaa02016a8685a06a0ee91f05a6277d9 < 68de7f3a38acab355c24114f77bf00d3094ce4da","Linux >= 67cc570edaa02016a8685a06a0ee91f05a6277d9 < 7904b94768e983bcb2be34a8d6d1f3450f5b838b","Linux 5.9"],"published":"2026-09-04","updated":"2026-10-03","sourceUpdated":"2026-10-03T11:17:40.277","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-80837","references":[{"url":"https://git.kernel.org/stable/c/68de7f3a38acab355c24114f77bf00d3094ce4da","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/6989f298103f575a768a85e4b19d2384709237f8","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/6fa88d11983c6fe693c13ed7c5b3b75ae9f39de6","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/7904b94768e983bcb2be34a8d6d1f3450f5b838b","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/df86c0e84025be8b6dd572a20852698927aa666b","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/e97e2d6d0b150fd78be573f9fdf193f204d9334e","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"}],"tags":["nvd","cve.org"],"epss":0.00209,"epssPercentile":0.09962,"ingestedAt":"2026-10-03T11:43:42.121Z","slug":"CVE-2026-80837","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: nf_tables: don't queue packet path object notifications\n\nAll file:line references below are against v7.2-rc4 (ac5b0e5651b1). The\ntrace was captured on 7.2.0-rc6-kasan72rc6 (075b74841bd0), where the same\nlines apply.\n\nnft_obj_notify() is exported and reached from the packet path. Its only\nin-tree caller is nft_quota_obj_eval() (net/netfilter/nft_quota.c:68),\nwhich notifies with GFP_ATOMIC while evaluating a rule for a transiting\npacket, holding no mutex.\n\nSince commit 67cc570edaa0 (\"netfilter: nf_tables: coalesce multiple\nnotifications into one skbuff\") that notification is no longer sent\nimmediately. __nft_obj_notify() queues it onto nft_net->notify_list via\nnft_notify_enqueue() (net/netfilter/nf_tables_api.c:1211), which is a bare\nlist_add_tail(). notify_list has no lock of its own\n(include/net/netfilter/nf_tables.h:1951), it is serialised by commit_mutex:\nthe six other enqueue sites all run inside a netlink transaction, and the\ndrain in nft_commit_notify() (net/netfilter/nf_tables_api.c:10746) does\nlist_del() + kfree_skb() from nf_tables_commit() with commit_mutex held.\n\nSending packets through a chain that references a depleted quota object\ntherefore races an unlocked list_add_tail() against list_del() +\nkfree_skb() on another CPU. The WRITE_ONCE(prev->next, new) in __list_add()\nthen stores through an sk_buff that has already been freed:\n\n  BUG: KASAN: slab-use-after-free in __nft_obj_notify+0x2c5/0x2d0\n  Write of size 8 at addr ff110001047183c0 by task poc/76\n  CPU: 0 UID: 1000 PID: 76 Comm: poc Tainted: G  W  7.2.0-rc6-kasan72rc6 #4\n  Call Trace:\n   <IRQ>\n   __nft_obj_notify (include/linux/list.h:164 include/linux/list.h:191\n                     net/netfilter/nf_tables_api.c:1211\n                     net/netfilter/nf_tables_api.c:8743)\n   nft_quota_obj_eval (net/netfilter/nft_quota.c:68)\n   nft_do_chain_inet\n   nf_hook_slow\n   __ip_local_out\n   ip_push_pending_frames\n   udp_send_skb\n   udp_sendmsg\n   __x64_sys_sendto\n\n  Allocated by task 77:\n   __alloc_skb (net/core/skbuff.c:704)\n   __nft_obj_notify (include/net/netlink.h:1055\n                     net/netfilter/nf_tables_api.c:8731)\n   nft_quota_obj_eval (net/netfilter/nft_quota.c:68)\n   nft_do_chain\n\n  Freed by task 79:\n   nf_tables_commit (include/linux/skbuff.h:1332\n                     net/netfilter/nf_tables_api.c:10759\n                     net/netfilter/nf_tables_api.c:11185)\n   nfnetlink_rcv_batch (net/netfilter/nfnetlink.c:574)\n   netlink_unicast\n   netlink_sendmsg\n\n  The buggy address belongs to the cache skbuff_head_cache of size 232\n\nQueueing from the packet path is wrong even leaving the race aside:\nnotify_list is only drained by nft_commit_notify() from nf_tables_commit()\n(:11185), so a notification enqueued outside a transaction is not sent\nuntil some later netlink batch commits, if one ever does.\n\nThe gfp argument that nft_obj_notify() still takes is a leftover of the\npre-67cc570edaa0 behaviour, where this path called nfnetlink_send()\ndirectly. Restore that: split the message construction out into\nnft_obj_notify_alloc() and let each caller decide what to do with the skb.\nnft_obj_notify(), the exported one reached from the packet path, sends it\nstraight away; nf_tables_obj_notify(), which runs under commit_mutex, keeps\nqueueing it, so transaction notifications are still coalesced.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":3,"depthScoreParts":{"impact":2.8,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}