{"id":"CVE-2026-43190","title":"netfilter: xt_tcpmss: check remaining length before reading optlen","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: xt_tcpmss: check remaining length before reading optlen\n\nQuoting reporter:\n  In net/netfilter/xt_tcpmss.c (lines 53-68), the TCP option parser reads\n op[i+1]…","severity":"high","cvss":8.2,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H","cvssSource":"cna","vendor":"Linux","product":"Linux","affected":["Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < f895191dc32c53eaf443b6443fe40945b2f92287","Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < cd5beda7e0e32865e214f28034bb92c1cecff885","Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < eaedc0bc18be46fe7f58170e967959a932c4f824","Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 07a9b32eaae792ff7d0fcac14d8920c937c0a9c3","Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 8b300f726640c48c3edfe9c453334dd801f4b74e","Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 5e13d0a37666955b6cfddc0f73cb40ed645b8a05","Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < f6c412dcfd76b0516d51aa847d8f4c7b70381b09","Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 735ee8582da3d239eb0c7a53adca61b79fb228b3","Linux 2.6.12"],"ssvc":{"exploitation":"none","automatable":"yes","technicalImpact":"partial","timestamp":"2026-10-16T15:15:30.447142Z"},"published":"2026-05-06","updated":"2026-10-16","sourceUpdated":"2026-10-16T15:20:35.750Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-43190","references":[{"url":"https://git.kernel.org/stable/c/f895191dc32c53eaf443b6443fe40945b2f92287"},{"url":"https://git.kernel.org/stable/c/cd5beda7e0e32865e214f28034bb92c1cecff885"},{"url":"https://git.kernel.org/stable/c/eaedc0bc18be46fe7f58170e967959a932c4f824"},{"url":"https://git.kernel.org/stable/c/07a9b32eaae792ff7d0fcac14d8920c937c0a9c3"},{"url":"https://git.kernel.org/stable/c/8b300f726640c48c3edfe9c453334dd801f4b74e"},{"url":"https://git.kernel.org/stable/c/5e13d0a37666955b6cfddc0f73cb40ed645b8a05"},{"url":"https://git.kernel.org/stable/c/f6c412dcfd76b0516d51aa847d8f4c7b70381b09"},{"url":"https://git.kernel.org/stable/c/735ee8582da3d239eb0c7a53adca61b79fb228b3"}],"tags":["cve.org"],"epss":0.00463,"epssPercentile":0.38686,"ingestedAt":"2026-10-16T17:24:46.686Z","slug":"CVE-2026-43190","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: xt_tcpmss: check remaining length before reading optlen\n\nQuoting reporter:\n  In net/netfilter/xt_tcpmss.c (lines 53-68), the TCP option parser reads\n op[i+1] directly without validating the remaining option length.\n\n  If the last byte of the option field is not EOL/NOP (0/1), the code attempts\n  to index op[i+1]. In the case where i + 1 == optlen, this causes an\n  out-of-bounds read, accessing memory past the optlen boundary\n  (either reading beyond the stack buffer _opt or the\n  following payload).\n\n## Affected\n\n- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < f895191dc32c53eaf443b6443fe40945b2f92287`\n- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < cd5beda7e0e32865e214f28034bb92c1cecff885`\n- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < eaedc0bc18be46fe7f58170e967959a932c4f824`\n- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 07a9b32eaae792ff7d0fcac14d8920c937c0a9c3`\n- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 8b300f726640c48c3edfe9c453334dd801f4b74e`\n- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 5e13d0a37666955b6cfddc0f73cb40ed645b8a05`\n- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < f6c412dcfd76b0516d51aa847d8f4c7b70381b09`\n- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 735ee8582da3d239eb0c7a53adca61b79fb228b3`\n- `Linux 2.6.12`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"twilight","depthScore":45,"depthScoreParts":{"impact":45.1,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}