{"id":"CVE-2026-80849","title":"net/tcp-ao: fix use-after-free of current_key on reconnect to another peer","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet/tcp-ao: fix use-after-free of current_key on reconnect to another peer\n\ntcp_inbound_ao_hash() is called before bh_lock_sock_nested() is taken,\nwith only rcu_read_lo…","severity":"none","vendor":"Linux","product":"Linux","affected":["Linux >= 0a3a809089eb1d4a0a2fd0c16b520d603988c859 < 84a93b4e012587d0a4a84ffb23ec6da18e9d85f9","Linux >= 0a3a809089eb1d4a0a2fd0c16b520d603988c859 < 73fde8fe4469f4ed8f0afcc0b9d6413002a9e6b3","Linux >= 0a3a809089eb1d4a0a2fd0c16b520d603988c859 < e54ad693eddb40c595add013f545354c538e325b","Linux >= 0a3a809089eb1d4a0a2fd0c16b520d603988c859 < 2857dcbd03cf3354af0fba1b65c6a260fb43811a","Linux >= 0a3a809089eb1d4a0a2fd0c16b520d603988c859 < da4471557f279d0f56605158a625bb6e49ef7d41","Linux 6.7"],"published":"2026-09-04","updated":"2026-10-19","sourceUpdated":"2026-10-19T08:44:43.405Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-80849","references":[{"url":"https://git.kernel.org/stable/c/84a93b4e012587d0a4a84ffb23ec6da18e9d85f9"},{"url":"https://git.kernel.org/stable/c/73fde8fe4469f4ed8f0afcc0b9d6413002a9e6b3"},{"url":"https://git.kernel.org/stable/c/e54ad693eddb40c595add013f545354c538e325b"},{"url":"https://git.kernel.org/stable/c/2857dcbd03cf3354af0fba1b65c6a260fb43811a"},{"url":"https://git.kernel.org/stable/c/da4471557f279d0f56605158a625bb6e49ef7d41"}],"tags":["cve.org"],"epss":0.00168,"epssPercentile":0.05678,"ingestedAt":"2026-10-19T09:16:01.495Z","slug":"CVE-2026-80849","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nnet/tcp-ao: fix use-after-free of current_key on reconnect to another peer\n\ntcp_inbound_ao_hash() is called before bh_lock_sock_nested() is taken,\nwith only rcu_read_lock() held. On the fast path for established\nsockets, if the rnext_keyid sent by the peer differs from\ncurrent_key->sndid, the key the peer asked for is looked up and stored\nin current_key. The lookup is inside the RCU read side, but current_key\noutlives it.\n\nWhen the socket is disconnected and connect() is called again for\nanother peer, tcp_ao_connect_init() unlinks every key that does not\nmatch the new peer and frees it with call_rcu(). If current_key points\nat such a key, it is cleared to NULL.\n\nThe fast path reads sk_state only once on entry, so a softirq that got\ninto it while the socket was still established can update current_key\nafter that loop has already run. The update is inside the RCU read side,\nso it comes before the call_rcu() callback, and once the callback frees\nthe key, current_key is left pointing at freed memory.\n\nThe next transmission picks that pointer up in tcp_get_current_key().\ntcp_ao_transmit_skb() then reads the traffic key from the freed object,\nwhich is the use-after-free.\n\nWait for one grace period before unlinking, and only if a key is going\nto be removed. By the time tcp_connect() runs the socket is already in\nTCP_SYN_SENT, and TCP_AO_ESTABLISHED does not contain TCPF_SYN_SENT, so\na softirq entering after the wait cannot reach the fast path, and the\nones already in it have finished. The existing NULL handling in the loop\nis then enough.\n\n## Affected\n\n- `Linux >= 0a3a809089eb1d4a0a2fd0c16b520d603988c859 < 84a93b4e012587d0a4a84ffb23ec6da18e9d85f9`\n- `Linux >= 0a3a809089eb1d4a0a2fd0c16b520d603988c859 < 73fde8fe4469f4ed8f0afcc0b9d6413002a9e6b3`\n- `Linux >= 0a3a809089eb1d4a0a2fd0c16b520d603988c859 < e54ad693eddb40c595add013f545354c538e325b`\n- `Linux >= 0a3a809089eb1d4a0a2fd0c16b520d603988c859 < 2857dcbd03cf3354af0fba1b65c6a260fb43811a`\n- `Linux >= 0a3a809089eb1d4a0a2fd0c16b520d603988c859 < da4471557f279d0f56605158a625bb6e49ef7d41`\n- `Linux 6.7`\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":[]}