{"schema":"threatline.record/2","record":{"id":"CVE-2026-99133","aliases":[],"summary":"net/iucv: fix the recvmsg window update","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet/iucv: fix the recvmsg window update\n\niucv_sock_recvmsg() sends the HiperSockets-only AF_IUCV_FLAG_WIN without\ntesting the transport, so on a classic z/VM socket iucv_send_ctrl() sizes\nthe skb through a NULL iucv->hs_dev. SO_MSGLIMIT accepts 1, so msglimit / 2\nis zero and one recvmsg() on its own socket is enough for an unprivileged\nprocess to take a spurious disconnect.\n\nIt also calls iucv_send_ctrl() under spin_lock_bh(&message_q.lock), which\nallocates GFP_KERNEL inside a section the code treats as atomic. Sending\noutside that lock lets two recvmsg() reach afiucv_hs_send() at once, where\nmsg_recv is sampled for the advertised window and subtracted after\ndev_queue_xmit() -- and sendmsg reaches that counter under lock_sock()\nwhile recvmsg holds no socket lock, so both can subtract the same value,\nthe counter goes negative and the credit reaches the peer twice.\n\nTest the transport, claim the credit with atomic_xchg() after the last\nerror exit and hand it back if the transmit fails, and send once the lock\nis dropped.","categories":["Operating systems"],"product":"Linux","vendor":"Linux","ecosystem":null,"affected_ranges":[{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-99133","source_modified_at":"2026-10-28T10:34:46.398Z","fetched_at":"2026-10-28T15:55:58.673066Z","product":"Linux","vendor":"Linux","versions":[{"version":"3881ac441f642d56503818123446f7298442236b","lessThan":"8f2efa742f4cfe7dd756154f8bc07350dbe3ec92","status":"affected","versionType":"git"},{"version":"3881ac441f642d56503818123446f7298442236b","lessThan":"fe7393a627db2d093e8c0cae69d619b30fefae5f","status":"affected","versionType":"git"},{"version":"3881ac441f642d56503818123446f7298442236b","lessThan":"fa5acd038ea657ad5033713d6916214cbd349151","status":"affected","versionType":"git"}],"defaultStatus":"unaffected"},{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-99133","source_modified_at":"2026-10-28T10:34:46.398Z","fetched_at":"2026-10-28T15:55:58.673066Z","product":"Linux","vendor":"Linux","versions":[{"version":"3.2","status":"affected"},{"version":"0","lessThan":"3.2","status":"unaffected","versionType":"semver"},{"version":"6.18.59","lessThanOrEqual":"6.18.*","status":"unaffected","versionType":"semver"},{"version":"7.2.13","lessThanOrEqual":"7.2.*","status":"unaffected","versionType":"semver"},{"version":"7.3","lessThanOrEqual":"*","status":"unaffected","versionType":"original_commit_for_fix"}],"defaultStatus":"affected"}],"fixed_versions":[{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-99133","source_modified_at":"2026-10-28T10:34:46.398Z","fetched_at":"2026-10-28T15:55:58.673066Z","package":{"name":"Linux","ecosystem":null},"version":"8f2efa742f4cfe7dd756154f8bc07350dbe3ec92","basis":"first unaffected version stated in the CVE record"}],"cvss":null,"severity":null,"kev":{"listed":false},"epss":{"probability":null,"percentile":null,"score_date":null},"published_at":"2026-10-28T10:34:46.398Z","modified_at":"2026-10-28T10:34:46.398Z","provenance":[{"source":"CVE List","url":"https://www.cve.org/CVERecord?id=CVE-2026-99133","fetched_at":"2026-10-28T15:55:58.673066Z","source_modified_at":"2026-10-28T10:34:46.398Z"}],"sources":["CVE List"],"references":[{"source":"CVE List","url":"https://git.kernel.org/stable/c/8f2efa742f4cfe7dd756154f8bc07350dbe3ec92"},{"source":"CVE List","url":"https://git.kernel.org/stable/c/fe7393a627db2d093e8c0cae69d619b30fefae5f"},{"source":"CVE List","url":"https://git.kernel.org/stable/c/fa5acd038ea657ad5033713d6916214cbd349151"}],"locations":[],"motoko_assessment":{"status":"requires_architecture_review","automatic_remediation":false},"cve_state":"PUBLISHED","classification":{"method":"product-first software-layer rules","rules_version":"2.1","matched_on":"product","confidence":"heuristic","reviewed":false},"change_timestamp":"2026-10-28T10:34:46.398Z","content_hash":"bcacbd5a48e3af08f9d8b041c8e68f4f6eb74b8217fee2e5e6f470ba30b19e30"}}