{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-98541", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-09-25T10:25:14.356Z", "datePublished": "2026-10-18T15:18:09.190Z", "dateUpdated": "2026-10-19T09:21:24.620Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-10-19T09:21:24.620Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nfou: reject omitted FOU_ATTR_IPPROTO on FOU_ENCAP_DIRECT\n\nCommit 7a9bc9e3f423 (\"fou: Don't allow 0 for FOU_ATTR_IPPROTO.\") added\nNLA_POLICY_MIN(NLA_U8, 1) to fou_nl_policy[FOU_ATTR_IPPROTO], which\nrejects an explicitly supplied FOU_ATTR_IPPROTO == 0 attribute with\n-ERANGE.\n\nHowever, FOU_ATTR_IPPROTO is an optional netlink attribute. When a user\nsends FOU_CMD_ADD with FOU_ATTR_TYPE set to FOU_ENCAP_DIRECT and omits\nFOU_ATTR_IPPROTO entirely, nla_policy validation succeeds and\nparse_nl_config() leaves cfg->protocol as 0 (from memset(cfg, 0,\nsizeof(*cfg))). fou_create() then creates a FOU_ENCAP_DIRECT socket with\nfou->protocol == 0.\n\nIn fou_udp_recv(), returning -fou->protocol to udp_queue_rcv_one_skb()\ntriggers IP protocol resubmission when fou->protocol > 0, whereas\nreturning 0 tells the UDP tunnel layer that the skb was consumed without\nfreeing it. When fou->protocol == 0, every packet received on the socket\nreturns 0 from fou_udp_recv() and leaks the sk_buff.\n\nReject FOU_ENCAP_DIRECT when !cfg->protocol in fou_create() so that\ncreating a direct encapsulation port without FOU_ATTR_IPPROTO fails with\n-EINVAL while leaving FOU_CMD_DEL and FOU_CMD_GET (which share\nparse_nl_config()) unaffected.\n\nTested in QEMU against Linux 7.3.0-rc3 by sending a FOU_CMD_ADD Generic\nNetlink request with FOU_ATTR_PORT = 5555 and FOU_ATTR_TYPE =\nFOU_ENCAP_DIRECT while omitting FOU_ATTR_IPPROTO. On the unfixed kernel,\nFOU_CMD_ADD succeeds (err = 0), FOU_CMD_GET reports fou->type = 1 and\nfou->protocol = 0, and sending 4000 UDP packets to 127.0.0.1:5555 leaks\nall 4000 sk_buffs (SUnreclaim in /proc/meminfo grows from 41456 kB to\n59008 kB, +17552 kB); with this patch applied, FOU_CMD_ADD is rejected\nwith -EINVAL (-22)." } ], "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": "fd20220f86947d66d4dba2d76f13a28dbd86ef30", "status": "affected", "versionType": "git" }, { "version": "23461551c00628c3f3fe9cf837bf53cf8f212b63", "lessThan": "46b1ffb7e169c7e401dd890b29e55dbc261f8f01", "status": "affected", "versionType": "git" }, { "version": "23461551c00628c3f3fe9cf837bf53cf8f212b63", "lessThan": "7f4ba56f5d310dd018972916167985010a5d66a1", "status": "affected", "versionType": "git" }, { "version": "23461551c00628c3f3fe9cf837bf53cf8f212b63", "lessThan": "3bcc1624cc1cdcc05b566475d6e848093ab2a8f6", "status": "affected", "versionType": "git" }, { "version": "23461551c00628c3f3fe9cf837bf53cf8f212b63", "lessThan": "8b43f40798bb2758489fbbcae7e841ad4443c213", "status": "affected", "versionType": "git" }, { "version": "23461551c00628c3f3fe9cf837bf53cf8f212b63", "lessThan": "b1229b210ef5a39c58be665e6798203751411842", "status": "affected", "versionType": "git" }, { "version": "23461551c00628c3f3fe9cf837bf53cf8f212b63", "lessThan": "520cf06b8ea0ba5bcc1b8b982ef07f02b5e56221", "status": "affected", "versionType": "git" }, { "version": "23461551c00628c3f3fe9cf837bf53cf8f212b63", "lessThan": "d22609f3d13fc5baacd92c222731b03c593401db", "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": "6.12.112", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.55", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.2.9", "lessThanOrEqual": "7.2.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.3", "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": "6.12.112" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.18", "versionEndExcluding": "6.18.55" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.18", "versionEndExcluding": "7.2.9" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.18", "versionEndExcluding": "7.3" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/fd20220f86947d66d4dba2d76f13a28dbd86ef30" }, { "url": "https://git.kernel.org/stable/c/46b1ffb7e169c7e401dd890b29e55dbc261f8f01" }, { "url": "https://git.kernel.org/stable/c/7f4ba56f5d310dd018972916167985010a5d66a1" }, { "url": "https://git.kernel.org/stable/c/3bcc1624cc1cdcc05b566475d6e848093ab2a8f6" }, { "url": "https://git.kernel.org/stable/c/8b43f40798bb2758489fbbcae7e841ad4443c213" }, { "url": "https://git.kernel.org/stable/c/b1229b210ef5a39c58be665e6798203751411842" }, { "url": "https://git.kernel.org/stable/c/520cf06b8ea0ba5bcc1b8b982ef07f02b5e56221" }, { "url": "https://git.kernel.org/stable/c/d22609f3d13fc5baacd92c222731b03c593401db" } ], "title": "fou: reject omitted FOU_ATTR_IPPROTO on FOU_ENCAP_DIRECT", "x_generator": { "engine": "bippy-1.2.0" } } } }