{"id":"CVE-2026-74434","aliases":[],"url":"https://o3.security/vulnerability/CVE-2026-74434","summary":"rxrpc: Don't move a peeked OOB message onto the pending queue","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nrxrpc: Don't move a peeked OOB message onto the pending queue\n\nrxrpc_recvmsg_oob() takes a received oob message off recvmsg_oobq and,\nif a response is needed, moves it onto the pending_oobq tree. However,\nonly the unlink from recvmsg_oobq is guarded by MSG_PEEK; the move onto\npending_oobq always runs.\n\nAs a result, reading a challenge with MSG_PEEK leaves the skb on\nrecvmsg_oobq while also adding it to pending_oobq. Since struct\nsk_buff's rbnode shares storage with its next and prev pointers,\nrb_insert_color() overwrites the list linkage, and the skb, which holds\na single reference, becomes reachable from both queues at once.\n\nWhen the socket is closed both queues are drained in turn. While\ndraining recvmsg_oobq, __skb_unlink() follows the next and prev\npointers that rbnode has overwritten and writes to a bad address. Also,\nas the skb holds a single reference but is freed from each queue, both\nthe skb and the connection reference it holds are released twice. This\nleads to memory corruption and to a use-after-free caused by the\nconnection refcount underflow.\n\nMSG_PEEK does not consume the message from the queue, so only unlink it\nfrom recvmsg_oobq and then move it onto pending_oobq or free it when\nthe message is actually consumed.","published":"2026-08-15T05:59:33.438Z","modified":"2026-08-18T03:56:48.201375404Z","cvss":{"score":9.8,"severity":"CRITICAL","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"},"epss":null,"cisaKev":null,"exploitsKnown":null,"affectedPackages":[{"ecosystem":"Linux","name":"Kernel","fixedVersion":"6.18.40"}],"fix":null,"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/5801cff7d5d7b4e9d877dfb627b23eb63167f02c"},{"type":"WEB","url":"https://git.kernel.org/stable/c/5f470cc883416fea6d3bce18ef96bf91dd49ffc3"},{"type":"WEB","url":"https://git.kernel.org/stable/c/9ada3931beb37068fcb725b34b0398457009f343"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/74xxx/CVE-2026-74434.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-74434"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-18T03:56:48.201375404Z"}}