{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-31504", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-03-09T15:48:24.105Z", "datePublished": "2026-04-22T13:54:23.862Z", "dateUpdated": "2026-08-05T12:23:07.003Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T12:23:07.003Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: fix fanout UAF in packet_release() via NETDEV_UP race\n\n`packet_release()` has a race window where `NETDEV_UP` can re-register a\nsocket into a fanout group's `arr[]` array. The re-registration is not\ncleaned up by `fanout_release()`, leaving a dangling pointer in the fanout\narray.\n`packet_release()` does NOT zero `po->num` in its `bind_lock` section.\nAfter releasing `bind_lock`, `po->num` is still non-zero and `po->ifindex`\nstill matches the bound device. A concurrent `packet_notifier(NETDEV_UP)`\nthat already found the socket in `sklist` can re-register the hook.\nFor fanout sockets, this re-registration calls `__fanout_link(sk, po)`\nwhich adds the socket back into `f->arr[]` and increments `f->num_members`,\nbut does NOT increment `f->sk_ref`.\n\nThe fix sets `po->num` to zero in `packet_release` while `bind_lock` is\nheld to prevent NETDEV_UP from linking, preventing the race window.\n\nThis bug was found following an additional audit with Claude Code based\non CVE-2025-38617." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "baseScore": 7.8, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:L - The vulnerable path is reached through local AF_PACKET socket setup, setsockopt(PACKET_FANOUT), close(), and local NETDEV_UP triggering, not by unauthenticated remote packets alone.\nAC:L - The attacker controls both sides of the race by closing/releasing AF_PACKET fanout sockets while concurrently toggling a controlled netdevice up, and can repeat the race with chosen fanout modes.\nPR:L - AF_PACKET creation requires CAP_NET_RAW and NETDEV_UP requires CAP_NET_ADMIN in the target network namespace; both are obtainable by an unprivileged user in a user/network namespace on affected systems.\nUI:N - No victim action is required once the local attacker can run code and issue the relevant syscalls.\nS:U - The bug corrupts kernel networking state and enables kernel compromise within the same kernel security authority; it is not a VM or hardware boundary escape.\nC:H - This is a kernel heap use-after-free involving stale packet fanout/socket pointers reachable from packet receive dispatch, and such UAFs can be shaped into kernel memory disclosure primitives.\nI:H - The dangling fanout entry can drive execution through freed or reclaimed packet socket state, making kernel memory corruption and control-flow or privilege-escalation primitives defensible.\nA:H - Even without full exploitation, the stale fanout/socket pointer can be dereferenced on packet delivery and cause a kernel oops, panic, or persistent crash." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/packet/af_packet.c" ], "versions": [ { "version": "ce06b03e60fc19c680d1bf873e779bf11c2fc518", "lessThan": "ee642b1962caa9aa231c01abbd58bc453ae6b66e", "status": "affected", "versionType": "git" }, { "version": "ce06b03e60fc19c680d1bf873e779bf11c2fc518", "lessThan": "42cfd7898eeed290c9fb73f732af1f7d6b0a703e", "status": "affected", "versionType": "git" }, { "version": "ce06b03e60fc19c680d1bf873e779bf11c2fc518", "lessThan": "1b4c03f8892d955385c202009af7485364731bb9", "status": "affected", "versionType": "git" }, { "version": "ce06b03e60fc19c680d1bf873e779bf11c2fc518", "lessThan": "654386baef228c2992dbf604c819e4c7c35fc71b", "status": "affected", "versionType": "git" }, { "version": "ce06b03e60fc19c680d1bf873e779bf11c2fc518", "lessThan": "75fe6db23705a1d55160081f7b37db9665b1880b", "status": "affected", "versionType": "git" }, { "version": "ce06b03e60fc19c680d1bf873e779bf11c2fc518", "lessThan": "d0c7cdc15fdf8c4f91aca1928e52295d175b6ec6", "status": "affected", "versionType": "git" }, { "version": "ce06b03e60fc19c680d1bf873e779bf11c2fc518", "lessThan": "ceccbfc6de720ad633519a226715989cfb065af1", "status": "affected", "versionType": "git" }, { "version": "ce06b03e60fc19c680d1bf873e779bf11c2fc518", "lessThan": "42156f93d123436f2a27c468f18c966b7e5db796", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/packet/af_packet.c" ], "versions": [ { "version": "3.1", "status": "affected" }, { "version": "0", "lessThan": "3.1", "status": "unaffected", "versionType": "semver" }, { "version": "5.10.253", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.203", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.168", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.131", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.80", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.21", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.19.11", "lessThanOrEqual": "6.19.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.0", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix" } ] } ], "cpeApplicability": [ { "nodes": [ { "operator": "OR", "negate": false, "cpeMatch": [ { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.1", "versionEndExcluding": "5.10.253" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.1", "versionEndExcluding": "5.15.203" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.1", "versionEndExcluding": "6.1.168" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.1", "versionEndExcluding": "6.6.131" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.1", "versionEndExcluding": "6.12.80" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.1", "versionEndExcluding": "6.18.21" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.1", "versionEndExcluding": "6.19.11" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.1", "versionEndExcluding": "7.0" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/ee642b1962caa9aa231c01abbd58bc453ae6b66e" }, { "url": "https://git.kernel.org/stable/c/42cfd7898eeed290c9fb73f732af1f7d6b0a703e" }, { "url": "https://git.kernel.org/stable/c/1b4c03f8892d955385c202009af7485364731bb9" }, { "url": "https://git.kernel.org/stable/c/654386baef228c2992dbf604c819e4c7c35fc71b" }, { "url": "https://git.kernel.org/stable/c/75fe6db23705a1d55160081f7b37db9665b1880b" }, { "url": "https://git.kernel.org/stable/c/d0c7cdc15fdf8c4f91aca1928e52295d175b6ec6" }, { "url": "https://git.kernel.org/stable/c/ceccbfc6de720ad633519a226715989cfb065af1" }, { "url": "https://git.kernel.org/stable/c/42156f93d123436f2a27c468f18c966b7e5db796" } ], "title": "net: fix fanout UAF in packet_release() via NETDEV_UP race", "x_generator": { "engine": "bippy-1.2.0" } }, "adp": [ { "x_adpType": "supplier", "providerMetadata": { "orgId": "0b142b55-0307-4c5a-b3c9-f314f3fb7c5e", "shortName": "siemens-SADP", "dateUpdated": "2026-07-14T12:48:08.943Z" }, "affected": [ { "vendor": "Siemens", "product": "SIMATIC S7-1500 CPU 1518-4 PN/DP MFP", "versions": [ { "status": "affected", "version": "V3.1.6", "lessThan": "*", "versionType": "custom" } ], "defaultStatus": "unknown" }, { "vendor": "Siemens", "product": "SIMATIC S7-1500 CPU 1518-4 PN/DP MFP", "versions": [ { "status": "affected", "version": "V3.1.5", "lessThan": "*", "versionType": "custom" } ], "defaultStatus": "unknown" }, { "vendor": "Siemens", "product": "SIMATIC S7-1500 CPU 1518-4 PN/DP MFP", "versions": [ { "status": "affected", "version": "V3.1.6", "lessThan": "*", "versionType": "custom" } ], "defaultStatus": "unknown" }, { "vendor": "Siemens", "product": "SIMATIC S7-1500 CPU 1518-4 PN/DP MFP", "versions": [ { "status": "affected", "version": "V3.1.5", "lessThan": "*", 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"affected", "version": "V3.1.6", "lessThan": "*", "versionType": "custom" } ], "defaultStatus": "unknown" }, { "vendor": "Siemens", "product": "SIPLUS S7-1500 CPU 1518-4 PN/DP MFP", "versions": [ { "status": "affected", "version": "V3.1.5", "lessThan": "*", "versionType": "custom" } ], "defaultStatus": "unknown" } ], "references": [ { "url": "https://cert-portal.siemens.com/productcert/html/ssa-082556.html" }, { "url": "https://cert-portal.siemens.com/productcert/html/ssa-019113.html" } ] } ] } }