{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-74496", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-08-15T05:44:03.906Z", "datePublished": "2026-08-15T12:27:23.854Z", "dateUpdated": "2026-10-16T19:05:50.395Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-10-03T10:56:03.355Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nfou: Fix use-after-free in fou_create()\n\nfou_create() publishes struct fou through sk_user_data before adding the\nnew FOU port to the per-netns list. If fou_add_to_port_list() fails,\nthe error path frees fou while it is still reachable through\nsk_user_data. A concurrent receive can then dereference the freed\nobject in fou_from_sock().\n\nThis ordering issue was previously noted in the linked discussion.\n\nThe failure is reachable when local port 0 is requested. Each socket\nbinds to a different ephemeral port, but fou_cfg_cmp() compares the\nrequested port 0 and reports -EALREADY once an entry already exists.\n\nRelease the tunnel socket before freeing fou so sk_user_data is cleared\nfirst, and defer reclamation with kfree_rcu() to protect concurrent RCU\nreaders. This matches the lifetime handling in fou_release()." } ], "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 UAF is opened only via local FOU_CMD_ADD genetlink into fou_create(); remote UDP can race the dangling sk_user_data read in fou_udp_recv/gue_udp_recv but cannot alone reach the erroneous teardown path.\nAC:L - An attacker with CAP_NET_ADMIN controls both sides: issue a second FOU_CMD_ADD with port 0 to force -EALREADY on fou_add_to_port_list while concurrently sending UDP/GRO traffic to the just-bound ephemeral socket during the kfree window.\nPR:L - FOU_CMD_ADD is gated by GENL_ADMIN_PERM (CAP_NET_ADMIN); the fou genl family is netnsok, so a user with CAP_NET_ADMIN inside unshare -Urn can configure FOU and trigger the failing add path without init-namespace root.\nUI:N - Exploitation is fully programmatic via concurrent netlink FOU_CMD_ADD requests and attacker-controlled UDP packets; no victim mount, file open, or other interactive action is required.\nS:U - Impact is kernel heap corruption and privilege escalation within the same security authority; this is not a VM escape, IOMMU bypass, or other cross-boundary scope change.\nC:H - Concurrent readers call fou_from_sock() and dereference freed struct fou fields (family, protocol, flags); reclaimed slab contents give attacker-controlled reads and kernel pointer disclosure primitives typical of UAF.\nI:H - Freed struct fou is attacker-reclaimable kmalloc memory; fou_gro_receive indexes inet_offloads[fou->protocol] from the dangling pointer, enabling heap grooming for arbitrary writes and control-flow hijack.\nA:H - Use-after-free in UDP receive/GRO softirq reliably causes KASAN violations and, on production kernels, invalid pointer dereferences or panics when accessing the freed fou object during packet processing." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/ipv4/fou_core.c" ], "versions": [ { "version": "23461551c00628c3f3fe9cf837bf53cf8f212b63", "lessThan": "0ee628a58d83e571f36ec9f07624d6845e420c50", "status": "affected", "versionType": "git" }, { "version": "23461551c00628c3f3fe9cf837bf53cf8f212b63", "lessThan": "a6fca682cfa2041e31aa72cc397c4a1406eb7468", "status": "affected", "versionType": "git" }, { "version": "23461551c00628c3f3fe9cf837bf53cf8f212b63", "lessThan": "b3f9c3e60aa25453774f899d25b5e61dd0bec1d5", "status": "affected", "versionType": "git" }, { "version": "23461551c00628c3f3fe9cf837bf53cf8f212b63", "lessThan": "99f4d3120b244f92e5df787152041296a2860cb5", "status": "affected", "versionType": "git" }, { "version": "23461551c00628c3f3fe9cf837bf53cf8f212b63", "lessThan": "58835985c035a8333742f829ad7e0889a082f9d3", "status": "affected", "versionType": "git" }, { "version": "23461551c00628c3f3fe9cf837bf53cf8f212b63", "lessThan": "9042867d4701728f0c6527215b11471759904d8f", "status": "affected", "versionType": "git" }, { "version": "23461551c00628c3f3fe9cf837bf53cf8f212b63", "lessThan": "a28d8903bfe76089ea4bbdbff9976965f9ef8107", "status": "affected", "versionType": "git" }, { "version": "23461551c00628c3f3fe9cf837bf53cf8f212b63", "lessThan": "b14361aca6350ff7907b0e9903c7b94dc7d5d4a0", "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/ipv4/fou_core.c" ], "versions": [ { "version": "3.18", "status": "affected" }, { "version": "0", "lessThan": "3.18", "status": "unaffected", "versionType": "semver" }, { "version": "5.10.271", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.222", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.189", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.158", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.111", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.53", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.1.8", "lessThanOrEqual": "7.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.2", "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": "3.18", "versionEndExcluding": "5.10.271" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.18", "versionEndExcluding": "5.15.222" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.18", "versionEndExcluding": "6.1.189" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.18", "versionEndExcluding": "6.6.158" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.18", "versionEndExcluding": "6.12.111" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.18", "versionEndExcluding": "6.18.53" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.18", "versionEndExcluding": "7.1.8" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.18", "versionEndExcluding": "7.2" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/0ee628a58d83e571f36ec9f07624d6845e420c50" }, { "url": "https://git.kernel.org/stable/c/a6fca682cfa2041e31aa72cc397c4a1406eb7468" }, { "url": "https://git.kernel.org/stable/c/b3f9c3e60aa25453774f899d25b5e61dd0bec1d5" }, { "url": "https://git.kernel.org/stable/c/99f4d3120b244f92e5df787152041296a2860cb5" }, { "url": "https://git.kernel.org/stable/c/58835985c035a8333742f829ad7e0889a082f9d3" }, { "url": "https://git.kernel.org/stable/c/9042867d4701728f0c6527215b11471759904d8f" }, { "url": "https://git.kernel.org/stable/c/a28d8903bfe76089ea4bbdbff9976965f9ef8107" }, { "url": "https://git.kernel.org/stable/c/b14361aca6350ff7907b0e9903c7b94dc7d5d4a0" } ], "title": "fou: Fix use-after-free in fou_create()", "x_generator": { "engine": "bippy-1.2.0" } }, "adp": [ { "metrics": [ { "other": { "type": "ssvc", "content": { "id": "CVE-2026-74496", "role": "CISA Coordinator", "options": [ { "Exploitation": "none" }, { "Automatable": "no" }, { "Technical Impact": "total" } ], "version": "2.0.3", "timestamp": "2026-10-16T18:58:18.343359Z" } } } ], "title": "CISA ADP Vulnrichment", "providerMetadata": { "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-10-16T19:05:50.395Z" } } ] } }