{"api_version":"1","generated_at":"2026-09-11T22:18:43+00:00","cve":"CVE-2026-81003","urls":{"html":"https://cve.report/CVE-2026-81003","api":"https://cve.report/api/cve/CVE-2026-81003.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-81003","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-81003"},"summary":{"title":"net/iucv: filter frames in afiucv_hs_rcv() by ingress device","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet/iucv: filter frames in afiucv_hs_rcv() by ingress device\n\nafiucv_hs_rcv() selects a socket from iucv_sk_list by matching four 8-byte\nname fields in the transport header alone. No check is made against the\nnet_device the frame arrived on.\n\nThis can cause a frame arriving on any netdev to be delivered to an AF_IUCV\nsocket. Three problems follow.\n\nFirst, a frame arriving over HiperSockets can be delivered to a socket\nbound to the classic z/VM IUCV transport, which has iucv->hs_dev == NULL.\niucv_sock_bind() takes the classic path whenever the requested userid\nmatches iucv_userid, even on a guest that also has a HiperSockets device\ncarrying the same identifier. The child socket created by\nafiucv_hs_callback_syn() for such a match inherits hs_dev = NULL and\ntransport = AF_IUCV_TRANS_HIPER, so the first send() on it returns -ENODEV.\nThe socket delivered to accept() is unusable.\n\nSecond, a frame arriving on one netdev can be delivered to a socket bound\nto a different IQD device. Which can lead to\n- Accept-queue exhaustion (DoS)\n- Attacker-controlled peer identity in the child socket\n- Data injection into existing sockets\n- Fabric noise on the IQD fabric, where bogus replies are sent\n- killing established connections\n\nThird, all AF_IUCV sockets live in init_net, as iucv_sock_alloc() calls\nsk_alloc(&init_net, ...). But even frames arriving on netdev devices in a\nnamespace can be delivered to an IUCV socket. So a process in an\nunprivileged user and network namespace holding only the CAP_NET_RAW\ncapability valid within that namespace can send a raw ETH_P_AF_IUCV frame\non its own lo device and have it matched against init_net sockets.\n\nFix all three by skipping any socket whose hs_dev does not match the\ningress device. A classic z/VM IUCV socket has hs_dev == NULL; the ingress\ndev is never NULL, so classic sockets are skipped automatically. An unbound\nHIPER socket also has hs_dev == NULL and is skipped. A bound HIPER socket\nis only reachable from the exact IQD device it was bound to. Because hs_dev\nis always a device in init_net (iucv_sock_bind() scans\nfor_each_netdev_rcu(&init_net, ...) exclusively), a frame whose ingress\ndevice belongs to another namespace never matches any socket.\n\nNote that AF_IUCV over HiperSockets provides no per-connection\nauthentication: no sequence numbers, no TLS, no nonce. The four name fields\nidentifying a connection are exchanged in plaintext on the shared\nHiperSockets segment (VCHID). Any host on the same HiperSockets segment\ncould spoof any frame type against an existing connection. That is a\nprotocol-level property unchanged by this patch. The fix reduces the attack\nsurface to peers present on the same HiperSockets segment.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-09-11 20:19:08","updated_at":"2026-09-11 20:19:08"},"problem_types":[],"metrics":[],"references":[{"url":"https://git.kernel.org/stable/c/dfac2936b83be00035ae176f8252e1c1e1de9207","name":"https://git.kernel.org/stable/c/dfac2936b83be00035ae176f8252e1c1e1de9207","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/80230a18c164a4b5bbc048fe2768b219ac17bc5a","name":"https://git.kernel.org/stable/c/80230a18c164a4b5bbc048fe2768b219ac17bc5a","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/a7f0130a091724e69827ab58e74777a88747e892","name":"https://git.kernel.org/stable/c/a7f0130a091724e69827ab58e74777a88747e892","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/8e3763f1ccac3fc395f9af2b87114c023ced8a3f","name":"https://git.kernel.org/stable/c/8e3763f1ccac3fc395f9af2b87114c023ced8a3f","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-81003","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-81003","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 3881ac441f642d56503818123446f7298442236b dfac2936b83be00035ae176f8252e1c1e1de9207 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 3881ac441f642d56503818123446f7298442236b 8e3763f1ccac3fc395f9af2b87114c023ced8a3f git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 3881ac441f642d56503818123446f7298442236b a7f0130a091724e69827ab58e74777a88747e892 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 3881ac441f642d56503818123446f7298442236b 80230a18c164a4b5bbc048fe2768b219ac17bc5a git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 3.2","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 3.2 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.12.109 6.12.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18.50 6.18.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.2.4 7.2.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.3-rc1 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":null,"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["net/iucv/af_iucv.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"dfac2936b83be00035ae176f8252e1c1e1de9207","status":"affected","version":"3881ac441f642d56503818123446f7298442236b","versionType":"git"},{"lessThan":"8e3763f1ccac3fc395f9af2b87114c023ced8a3f","status":"affected","version":"3881ac441f642d56503818123446f7298442236b","versionType":"git"},{"lessThan":"a7f0130a091724e69827ab58e74777a88747e892","status":"affected","version":"3881ac441f642d56503818123446f7298442236b","versionType":"git"},{"lessThan":"80230a18c164a4b5bbc048fe2768b219ac17bc5a","status":"affected","version":"3881ac441f642d56503818123446f7298442236b","versionType":"git"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["net/iucv/af_iucv.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"3.2"},{"lessThan":"3.2","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"6.12.*","status":"unaffected","version":"6.12.109","versionType":"semver"},{"lessThanOrEqual":"6.18.*","status":"unaffected","version":"6.18.50","versionType":"semver"},{"lessThanOrEqual":"7.2.*","status":"unaffected","version":"7.2.4","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.3-rc1","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.12.109","versionStartIncluding":"3.2","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.18.50","versionStartIncluding":"3.2","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.2.4","versionStartIncluding":"3.2","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.3-rc1","versionStartIncluding":"3.2","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet/iucv: filter frames in afiucv_hs_rcv() by ingress device\n\nafiucv_hs_rcv() selects a socket from iucv_sk_list by matching four 8-byte\nname fields in the transport header alone. No check is made against the\nnet_device the frame arrived on.\n\nThis can cause a frame arriving on any netdev to be delivered to an AF_IUCV\nsocket. Three problems follow.\n\nFirst, a frame arriving over HiperSockets can be delivered to a socket\nbound to the classic z/VM IUCV transport, which has iucv->hs_dev == NULL.\niucv_sock_bind() takes the classic path whenever the requested userid\nmatches iucv_userid, even on a guest that also has a HiperSockets device\ncarrying the same identifier. The child socket created by\nafiucv_hs_callback_syn() for such a match inherits hs_dev = NULL and\ntransport = AF_IUCV_TRANS_HIPER, so the first send() on it returns -ENODEV.\nThe socket delivered to accept() is unusable.\n\nSecond, a frame arriving on one netdev can be delivered to a socket bound\nto a different IQD device. Which can lead to\n- Accept-queue exhaustion (DoS)\n- Attacker-controlled peer identity in the child socket\n- Data injection into existing sockets\n- Fabric noise on the IQD fabric, where bogus replies are sent\n- killing established connections\n\nThird, all AF_IUCV sockets live in init_net, as iucv_sock_alloc() calls\nsk_alloc(&init_net, ...). But even frames arriving on netdev devices in a\nnamespace can be delivered to an IUCV socket. So a process in an\nunprivileged user and network namespace holding only the CAP_NET_RAW\ncapability valid within that namespace can send a raw ETH_P_AF_IUCV frame\non its own lo device and have it matched against init_net sockets.\n\nFix all three by skipping any socket whose hs_dev does not match the\ningress device. A classic z/VM IUCV socket has hs_dev == NULL; the ingress\ndev is never NULL, so classic sockets are skipped automatically. An unbound\nHIPER socket also has hs_dev == NULL and is skipped. A bound HIPER socket\nis only reachable from the exact IQD device it was bound to. Because hs_dev\nis always a device in init_net (iucv_sock_bind() scans\nfor_each_netdev_rcu(&init_net, ...) exclusively), a frame whose ingress\ndevice belongs to another namespace never matches any socket.\n\nNote that AF_IUCV over HiperSockets provides no per-connection\nauthentication: no sequence numbers, no TLS, no nonce. The four name fields\nidentifying a connection are exchanged in plaintext on the shared\nHiperSockets segment (VCHID). Any host on the same HiperSockets segment\ncould spoof any frame type against an existing connection. That is a\nprotocol-level property unchanged by this patch. The fix reduces the attack\nsurface to peers present on the same HiperSockets segment."}],"providerMetadata":{"dateUpdated":"2026-09-11T19:42:56.172Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/dfac2936b83be00035ae176f8252e1c1e1de9207"},{"url":"https://git.kernel.org/stable/c/8e3763f1ccac3fc395f9af2b87114c023ced8a3f"},{"url":"https://git.kernel.org/stable/c/a7f0130a091724e69827ab58e74777a88747e892"},{"url":"https://git.kernel.org/stable/c/80230a18c164a4b5bbc048fe2768b219ac17bc5a"}],"title":"net/iucv: filter frames in afiucv_hs_rcv() by ingress device","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-81003","datePublished":"2026-09-11T19:42:56.172Z","dateReserved":"2026-08-26T14:34:25.812Z","dateUpdated":"2026-09-11T19:42:56.172Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-09-11 20:19:08","lastModifiedDate":"2026-09-11 20:19:08","problem_types":[],"metrics":[],"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"81003","Ordinal":"1","Title":"net/iucv: filter frames in afiucv_hs_rcv() by ingress device","CVE":"CVE-2026-81003","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"81003","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet/iucv: filter frames in afiucv_hs_rcv() by ingress device\n\nafiucv_hs_rcv() selects a socket from iucv_sk_list by matching four 8-byte\nname fields in the transport header alone. No check is made against the\nnet_device the frame arrived on.\n\nThis can cause a frame arriving on any netdev to be delivered to an AF_IUCV\nsocket. Three problems follow.\n\nFirst, a frame arriving over HiperSockets can be delivered to a socket\nbound to the classic z/VM IUCV transport, which has iucv->hs_dev == NULL.\niucv_sock_bind() takes the classic path whenever the requested userid\nmatches iucv_userid, even on a guest that also has a HiperSockets device\ncarrying the same identifier. The child socket created by\nafiucv_hs_callback_syn() for such a match inherits hs_dev = NULL and\ntransport = AF_IUCV_TRANS_HIPER, so the first send() on it returns -ENODEV.\nThe socket delivered to accept() is unusable.\n\nSecond, a frame arriving on one netdev can be delivered to a socket bound\nto a different IQD device. Which can lead to\n- Accept-queue exhaustion (DoS)\n- Attacker-controlled peer identity in the child socket\n- Data injection into existing sockets\n- Fabric noise on the IQD fabric, where bogus replies are sent\n- killing established connections\n\nThird, all AF_IUCV sockets live in init_net, as iucv_sock_alloc() calls\nsk_alloc(&init_net, ...). But even frames arriving on netdev devices in a\nnamespace can be delivered to an IUCV socket. So a process in an\nunprivileged user and network namespace holding only the CAP_NET_RAW\ncapability valid within that namespace can send a raw ETH_P_AF_IUCV frame\non its own lo device and have it matched against init_net sockets.\n\nFix all three by skipping any socket whose hs_dev does not match the\ningress device. A classic z/VM IUCV socket has hs_dev == NULL; the ingress\ndev is never NULL, so classic sockets are skipped automatically. An unbound\nHIPER socket also has hs_dev == NULL and is skipped. A bound HIPER socket\nis only reachable from the exact IQD device it was bound to. Because hs_dev\nis always a device in init_net (iucv_sock_bind() scans\nfor_each_netdev_rcu(&init_net, ...) exclusively), a frame whose ingress\ndevice belongs to another namespace never matches any socket.\n\nNote that AF_IUCV over HiperSockets provides no per-connection\nauthentication: no sequence numbers, no TLS, no nonce. The four name fields\nidentifying a connection are exchanged in plaintext on the shared\nHiperSockets segment (VCHID). Any host on the same HiperSockets segment\ncould spoof any frame type against an existing connection. That is a\nprotocol-level property unchanged by this patch. The fix reduces the attack\nsurface to peers present on the same HiperSockets segment.","Type":"Description","Title":"net/iucv: filter frames in afiucv_hs_rcv() by ingress device"}]}}}