{"id":"CVE-2025-39894","revision":"5b729371c3114773a5daffac7b9bc27d","records":[{"revision":"5b729371c3114773a5daffac7b9bc27d","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2025-39894","aliases":[],"title":"netfilter: br_netfilter: do not check confirmed bit in br_nf_local_in() after confirm","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: br_netfilter: do not check confirmed bit in br_nf_local_in() after confirm\n\nWhen send a broadcast packet to a tap device, which was added to a bridge,\nbr_nf_local_in() is called to confirm the conntrack. If another conntrack\nwith the same hash value is added to the hash table, which can be\ntriggered by a normal packet to a non-bridge device, the below warning\nmay happen.\n\n ------------[ cut here ]------------\n WARNING: CPU: 1 PID: 96 at net/bridge/br_netfilter_hooks.c:632 br_nf_local_in+0x168/0x200\n CPU: 1 UID: 0 PID: 96 Comm: tap_send Not tainted 6.17.0-rc2-dirty #44 PREEMPT(voluntary)\n RIP: 0010:br_nf_local_in+0x168/0x200\n Call Trace:\n \n nf_hook_slow+0x3e/0xf0\n br_pass_frame_up+0x103/0x180\n br_handle_frame_finish+0x2de/0x5b0\n br_nf_hook_thresh+0xc0/0x120\n br_nf_pre_routing_finish+0x168/0x3a0\n br_nf_pre_routing+0x237/0x5e0\n br_handle_frame+0x1ec/0x3c0\n __netif_receive_skb_core+0x225/0x1210\n __netif_receive_skb_one_core+0x37/0xa0\n netif_receive_skb+0x36/0x160\n tun_get_user+0xa54/0x10c0\n tun_chr_write_iter+0x65/0xb0\n vfs_write+0x305/0x410\n ksys_write+0x60/0xd0\n do_syscall_64+0xa4/0x260\n entry_SYSCALL_64_after_hwframe+0x77/0x7f\n \n ---[ end trace 0000000000000000 ]---\n\nTo solve the hash conflict, nf_ct_resolve_clash() try to merge the\nconntracks, and update skb->_nfct. However, br_nf_local_in() still use the\nold ct from local variable 'nfct' after confirm(), which leads to this\nwarning.\n\nIf confirm() does not insert the conntrack entry and return NF_DROP, the\nwarning may also occur. There is no need to reserve the WARN_ON_ONCE, just\nremove it.","state":0,"publishedAt":"2025-10-01T07:42:43.126+00:00","modifiedAt":"2026-10-15T22:02:32.869+00:00","affected":[{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n \"product\": \"Linux\",\n \"vendor\": \"Linux\",\n \"defaultStatus\": \"unaffected\",\n \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n \"programFiles\": [\n \"net/bridge/br_netfilter_hooks.c\"\n ],\n \"versions\": [\n {\n \"version\": \"7c3f28599652acf431a2211168de4a583f30b6d5\",\n \"lessThan\": \"d00c8b0daf56012f69075e3377da67878c775e4c\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"2b1414d5e94e477edff1d2c79030f1d742625ea0\",\n \"lessThan\": \"ccbad4803225eafe0175d3cb19f0d8d73b504a94\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"80cd0487f630b5382734997c3e5e3003a77db315\",\n \"lessThan\": \"50db11e2bbb635e38e3dd096215580d6adb41fb0\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"62e7151ae3eb465e0ab52a20c941ff33bb6332e9\",\n \"lessThan\": \"c47ca77fee9071aa543bae592dd2a384f895c8b6\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"62e7151ae3eb465e0ab52a20c941ff33bb6332e9\",\n \"lessThan\": \"a74abcf0f09f59daeecf7a3ba9c1d690808b0afe\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"62e7151ae3eb465e0ab52a20c941ff33bb6332e9\",\n \"lessThan\": \"479a54ab92087318514c82428a87af2d7af1a576\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"cb734975b0ffa688ff6cc0eed463865bf07b6c01\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"5.15.151\",\n \"lessThan\": \"5.15.192\",\n \"status\": \"affected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.1.81\",\n \"lessThan\": \"6.1.151\",\n \"status\": \"affected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.6.21\",\n \"lessThan\": \"6.6.105\",\n \"status\": \"affected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.7.9\",\n \"lessThan\": \"6.8\",\n \"status\": \"affected\",\n \"versionType\": \"semver\"\n }\n ]\n }"},{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n \"product\": \"Linux\",\n \"vendor\": \"Linux\",\n \"defaultStatus\": \"affected\",\n \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n \"programFiles\": [\n \"net/bridge/br_netfilter_hooks.c\"\n ],\n \"versions\": [\n {\n \"version\": \"6.8\",\n \"status\": \"affected\"\n },\n {\n \"version\": \"0\",\n \"lessThan\": \"6.8\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"5.15.192\",\n \"lessThanOrEqual\": \"5.15.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.1.151\",\n \"lessThanOrEqual\": \"6.1.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.6.105\",\n \"lessThanOrEqual\": \"6.6.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.12.46\",\n \"lessThanOrEqual\": \"6.12.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.16.6\",\n \"lessThanOrEqual\": \"6.16.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.17\",\n \"lessThanOrEqual\": \"*\",\n \"status\": \"unaffected\",\n \"versionType\": \"original_commit_for_fix\"\n }\n ]\n }"}],"metrics":[{"system":"CVSS 3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","score":7.5,"severity":"HIGH"}],"references":["https://git.kernel.org/stable/c/d00c8b0daf56012f69075e3377da67878c775e4c","https://git.kernel.org/stable/c/ccbad4803225eafe0175d3cb19f0d8d73b504a94","https://git.kernel.org/stable/c/50db11e2bbb635e38e3dd096215580d6adb41fb0","https://git.kernel.org/stable/c/c47ca77fee9071aa543bae592dd2a384f895c8b6","https://git.kernel.org/stable/c/a74abcf0f09f59daeecf7a3ba9c1d690808b0afe","https://git.kernel.org/stable/c/479a54ab92087318514c82428a87af2d7af1a576"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2025-39894","license":"CVE Program Terms of Use","key":"cve-program:CVE-2025-39894","identifiers":["CVE-2025-39894"]},"retained":false,"historicalAffected":[]}],"coverage":[]}