{"id":"CVE-2026-99133","revision":"c71d5a32c3b14ef8a50355fb88c2a713","records":[{"revision":"c71d5a32c3b14ef8a50355fb88c2a713","observedAt":"2026-10-30T13:45:33.454+00:00","statement":{"source":"cve-program","id":"CVE-2026-99133","aliases":[],"title":"net/iucv: fix the recvmsg window update","description":"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.","state":0,"publishedAt":"2026-10-28T10:34:46.398+00:00","modifiedAt":"2026-10-30T12:42:06.467+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/iucv/af_iucv.c\"\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"3881ac441f642d56503818123446f7298442236b\",\n                            \"lessThan\": \"01123990f59ce32a1a5e690a4aeee002e932bb07\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"3881ac441f642d56503818123446f7298442236b\",\n                            \"lessThan\": \"1ebe68bbf8e75eeccaca0c7bc9694f5bc0c3f00a\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"3881ac441f642d56503818123446f7298442236b\",\n                            \"lessThan\": \"23e7fbbdca5aaba2a9a7bb9e4f2dc179c290ee76\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"3881ac441f642d56503818123446f7298442236b\",\n                            \"lessThan\": \"ce8aac3eb57f5366fa082b7cb8a1ac5652274f37\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"3881ac441f642d56503818123446f7298442236b\",\n                            \"lessThan\": \"8f2efa742f4cfe7dd756154f8bc07350dbe3ec92\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"3881ac441f642d56503818123446f7298442236b\",\n                            \"lessThan\": \"fe7393a627db2d093e8c0cae69d619b30fefae5f\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"3881ac441f642d56503818123446f7298442236b\",\n                            \"lessThan\": \"fa5acd038ea657ad5033713d6916214cbd349151\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\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/iucv/af_iucv.c\"\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"3.2\",\n                            \"status\": \"affected\"\n                        },\n                        {\n                            \"version\": \"0\",\n                            \"lessThan\": \"3.2\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"5.15.224\",\n                            \"lessThanOrEqual\": \"5.15.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.1.191\",\n                            \"lessThanOrEqual\": \"6.1.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.6.161\",\n                            \"lessThanOrEqual\": \"6.6.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.12.115\",\n                            \"lessThanOrEqual\": \"6.12.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.18.59\",\n                            \"lessThanOrEqual\": \"6.18.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"7.2.13\",\n                            \"lessThanOrEqual\": \"7.2.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"7.3\",\n                            \"lessThanOrEqual\": \"*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"original_commit_for_fix\"\n                        }\n                    ]\n                }"}],"metrics":[],"references":["https://git.kernel.org/stable/c/01123990f59ce32a1a5e690a4aeee002e932bb07","https://git.kernel.org/stable/c/1ebe68bbf8e75eeccaca0c7bc9694f5bc0c3f00a","https://git.kernel.org/stable/c/23e7fbbdca5aaba2a9a7bb9e4f2dc179c290ee76","https://git.kernel.org/stable/c/ce8aac3eb57f5366fa082b7cb8a1ac5652274f37","https://git.kernel.org/stable/c/8f2efa742f4cfe7dd756154f8bc07350dbe3ec92","https://git.kernel.org/stable/c/fe7393a627db2d093e8c0cae69d619b30fefae5f","https://git.kernel.org/stable/c/fa5acd038ea657ad5033713d6916214cbd349151"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-99133","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-99133","identifiers":["CVE-2026-99133"]},"retained":false,"historicalAffected":[]}],"coverage":[]}