{"id":"CVE-2026-53221","state":"PUBLISHED","title":"ip6_vti: fix incorrect tunnel matching in vti6_tnl_lookup()","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nip6_vti: fix incorrect tunnel matching in vti6_tnl_lookup()\n\nIn vti6_tnl_lookup(), when an exact match for a tunnel fails,\nthe code falls back to searching for wildcard tunnels:\n\n- Tunnels matching the packet's local address, with any remote address\n  wildcard remote).\n\n- Tunnels matching the packet's remote address, with any local address\n  (wildcard local).\n\nHowever, vti6 stores all these different types of tunnels in the same\nhash table (ip6n->tnls_r_l) prone to hash collisions.\n\nThe bug is that the fallback search loops in vti6_tnl_lookup() were\nmissing checks to ensure that the candidate tunnel actually has\na wildcard address.","publishedAt":"2026-06-25T08:39:23.177Z","updatedAt":"2026-10-19T19:57:29.527Z","severity":{"score":9.8,"label":"Critical","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"fbe68ee87522f6eaa10f9076c0a7117e1613f2f7","status":"affected","lessThan":"c327fa4fca31415431202e063767a7ae342e19c6","versionType":"git"},{"version":"fbe68ee87522f6eaa10f9076c0a7117e1613f2f7","status":"affected","lessThan":"fc657ac0767c49839b3ef0b08dc0953ca30883f8","versionType":"git"},{"version":"fbe68ee87522f6eaa10f9076c0a7117e1613f2f7","status":"affected","lessThan":"47fb3c2b4203556308e64354b3e78f2ce221d646","versionType":"git"},{"version":"fbe68ee87522f6eaa10f9076c0a7117e1613f2f7","status":"affected","lessThan":"f513f308cc4bdb4530d033431592ffbc29b7fca1","versionType":"git"},{"version":"fbe68ee87522f6eaa10f9076c0a7117e1613f2f7","status":"affected","lessThan":"90fd4513315ca07da99cfd8549d3e553a7160f0d","versionType":"git"},{"version":"fbe68ee87522f6eaa10f9076c0a7117e1613f2f7","status":"affected","lessThan":"2abfb19bbb81958714ad1d43ebeb65b30394184b","versionType":"git"},{"version":"fbe68ee87522f6eaa10f9076c0a7117e1613f2f7","status":"affected","lessThan":"2fc7bc087cc7085368263d9d37bfe9a0bddd6a2d","versionType":"git"},{"version":"fbe68ee87522f6eaa10f9076c0a7117e1613f2f7","status":"affected","lessThan":"a5c0359f5cbc51a2e2b114d6041e0f3c73f903e9","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/ipv6/ip6_vti.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"3.19","status":"affected"},{"version":"0","status":"unaffected","lessThan":"3.19","versionType":"semver"},{"version":"5.10.259","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.210","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.176","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.143","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.94","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.36","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.0.13","status":"unaffected","lessThanOrEqual":"7.0.*","versionType":"semver"},{"version":"7.1","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/ipv6/ip6_vti.c"]}],"references":["https://git.kernel.org/stable/c/c327fa4fca31415431202e063767a7ae342e19c6","https://git.kernel.org/stable/c/fc657ac0767c49839b3ef0b08dc0953ca30883f8","https://git.kernel.org/stable/c/47fb3c2b4203556308e64354b3e78f2ce221d646","https://git.kernel.org/stable/c/f513f308cc4bdb4530d033431592ffbc29b7fca1","https://git.kernel.org/stable/c/90fd4513315ca07da99cfd8549d3e553a7160f0d","https://git.kernel.org/stable/c/2abfb19bbb81958714ad1d43ebeb65b30394184b","https://git.kernel.org/stable/c/2fc7bc087cc7085368263d9d37bfe9a0bddd6a2d","https://git.kernel.org/stable/c/a5c0359f5cbc51a2e2b114d6041e0f3c73f903e9","https://cert-portal.siemens.com/productcert/html/ssa-784472.html"],"weaknesses":["CWE-20"],"ingestedAt":"2026-10-29T20:12:16.098Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/53xxx/CVE-2026-53221.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-53221","state":"PUBLISHED","datePublished":"2026-06-25T08:39:23.177Z","dateUpdated":"2026-10-19T19:57:29.527Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-06-09T07:44:35.392Z"},"containers":{"cna":{"title":"ip6_vti: fix incorrect tunnel matching in vti6_tnl_lookup()","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nip6_vti: fix incorrect tunnel matching in vti6_tnl_lookup()\n\nIn vti6_tnl_lookup(), when an exact match for a tunnel fails,\nthe code falls back to searching for wildcard tunnels:\n\n- Tunnels matching the packet's local address, with any remote address\n  wildcard remote).\n\n- Tunnels matching the packet's remote address, with any local address\n  (wildcard local).\n\nHowever, vti6 stores all these different types of tunnels in the same\nhash table (ip6n->tnls_r_l) prone to hash collisions.\n\nThe bug is that the fallback search loops in vti6_tnl_lookup() were\nmissing checks to ensure that the candidate tunnel actually has\na wildcard address."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"fbe68ee87522f6eaa10f9076c0a7117e1613f2f7","status":"affected","lessThan":"c327fa4fca31415431202e063767a7ae342e19c6","versionType":"git"},{"version":"fbe68ee87522f6eaa10f9076c0a7117e1613f2f7","status":"affected","lessThan":"fc657ac0767c49839b3ef0b08dc0953ca30883f8","versionType":"git"},{"version":"fbe68ee87522f6eaa10f9076c0a7117e1613f2f7","status":"affected","lessThan":"47fb3c2b4203556308e64354b3e78f2ce221d646","versionType":"git"},{"version":"fbe68ee87522f6eaa10f9076c0a7117e1613f2f7","status":"affected","lessThan":"f513f308cc4bdb4530d033431592ffbc29b7fca1","versionType":"git"},{"version":"fbe68ee87522f6eaa10f9076c0a7117e1613f2f7","status":"affected","lessThan":"90fd4513315ca07da99cfd8549d3e553a7160f0d","versionType":"git"},{"version":"fbe68ee87522f6eaa10f9076c0a7117e1613f2f7","status":"affected","lessThan":"2abfb19bbb81958714ad1d43ebeb65b30394184b","versionType":"git"},{"version":"fbe68ee87522f6eaa10f9076c0a7117e1613f2f7","status":"affected","lessThan":"2fc7bc087cc7085368263d9d37bfe9a0bddd6a2d","versionType":"git"},{"version":"fbe68ee87522f6eaa10f9076c0a7117e1613f2f7","status":"affected","lessThan":"a5c0359f5cbc51a2e2b114d6041e0f3c73f903e9","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/ipv6/ip6_vti.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"3.19","status":"affected"},{"version":"0","status":"unaffected","lessThan":"3.19","versionType":"semver"},{"version":"5.10.259","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.210","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.176","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.143","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.94","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.36","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.0.13","status":"unaffected","lessThanOrEqual":"7.0.*","versionType":"semver"},{"version":"7.1","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/ipv6/ip6_vti.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/c327fa4fca31415431202e063767a7ae342e19c6"},{"url":"https://git.kernel.org/stable/c/fc657ac0767c49839b3ef0b08dc0953ca30883f8"},{"url":"https://git.kernel.org/stable/c/47fb3c2b4203556308e64354b3e78f2ce221d646"},{"url":"https://git.kernel.org/stable/c/f513f308cc4bdb4530d033431592ffbc29b7fca1"},{"url":"https://git.kernel.org/stable/c/90fd4513315ca07da99cfd8549d3e553a7160f0d"},{"url":"https://git.kernel.org/stable/c/2abfb19bbb81958714ad1d43ebeb65b30394184b"},{"url":"https://git.kernel.org/stable/c/2fc7bc087cc7085368263d9d37bfe9a0bddd6a2d"},{"url":"https://git.kernel.org/stable/c/a5c0359f5cbc51a2e2b114d6041e0f3c73f903e9"}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","baseScore":9.8,"baseSeverity":"CRITICAL"},"scenarios":[{"lang":"en","value":"AV:N - The vulnerable lookup is reached from IPv6 packet input through registered XFRM ESP/AH/IPComp and IP-in-IPv6 tunnel handlers, so a remote peer can trigger it with network traffic.\nAC:L - The bug is a deterministic missing wildcard-address check in a small hash table; once a plausible VTI6 configuration with colliding wildcard/exact tunnel entries exists, chosen packets reliably exercise the wrong lookup.\nPR:N - The packet receive path reaches `vti6_tnl_lookup()` before any per-packet authentication succeeds, and no local privilege is needed to send the triggering IPv6 traffic.\nUI:N - No victim user action is required; packets are processed by the kernel networking receive path.\nS:U - The impact remains within the kernel/networking security authority and does not by itself cross a VM, IOMMU, or host boundary.\nC:H - Wrong tunnel selection can associate decapsulated traffic with another VTI device, mark, and policy context; in a multi-tenant IPsec/VTI gateway this can expose tunneled plaintext across tunnel boundaries.\nI:H - The same confusion can deliver attacker-controlled inner packets under the wrong tunnel interface and policy context, enabling unauthorized modification or injection of traffic in the affected tunnel domain.\nA:H - Incorrect matching can consistently drop or misprocess traffic for affected tunnels, allowing loss of availability of the VTI/IPsec connectivity in vulnerable 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