{"id":"CVE-2026-72400","title":"seg6: validate SRH length before reading fixed fields","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nseg6: validate SRH length before reading fixed fields\n\nseg6_validate_srh() reads fixed SRH fields such as srh->type and\nsrh->hdrlen before checking that the supplied le…","severity":"high","cvss":7.8,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","cvssSource":"cna","vendor":"Linux","product":"Linux","affected":["Linux >= fe94cc290f535709d3c5ebd1e472dfd0aec7ee79 < 715eb12e453df752f1b4baaf972c3acff0ab9402","Linux >= fe94cc290f535709d3c5ebd1e472dfd0aec7ee79 < 7247d05c987c3eec4bb7c2306dbd77ecdf3b7c73","Linux >= fe94cc290f535709d3c5ebd1e472dfd0aec7ee79 < 071f1a38d7ddbadee29c09b9e3ee0ff3a61e6a0e","Linux >= fe94cc290f535709d3c5ebd1e472dfd0aec7ee79 < 804bb969f194c93497ba632b98343794c6367fdc","Linux >= fe94cc290f535709d3c5ebd1e472dfd0aec7ee79 < 0fc7069d39239978130c37ebceaec85c8948d3f1","Linux >= fe94cc290f535709d3c5ebd1e472dfd0aec7ee79 < 8dba7a94a269b88e500aafc25ad567ef6a423698","Linux >= fe94cc290f535709d3c5ebd1e472dfd0aec7ee79 < c9961336aa5ff83092f23e33ee86666a9dbd1b2a","Linux >= fe94cc290f535709d3c5ebd1e472dfd0aec7ee79 < a75d99f46bf21b45965ce39c5cfb3b8bb5ffb1aa","Linux 4.18"],"ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"total","timestamp":"2026-10-16T18:48:57.930959Z"},"published":"2026-08-15","updated":"2026-10-16","sourceUpdated":"2026-10-16T18:55:21.670Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-72400","references":[{"url":"https://git.kernel.org/stable/c/715eb12e453df752f1b4baaf972c3acff0ab9402"},{"url":"https://git.kernel.org/stable/c/7247d05c987c3eec4bb7c2306dbd77ecdf3b7c73"},{"url":"https://git.kernel.org/stable/c/071f1a38d7ddbadee29c09b9e3ee0ff3a61e6a0e"},{"url":"https://git.kernel.org/stable/c/804bb969f194c93497ba632b98343794c6367fdc"},{"url":"https://git.kernel.org/stable/c/0fc7069d39239978130c37ebceaec85c8948d3f1"},{"url":"https://git.kernel.org/stable/c/8dba7a94a269b88e500aafc25ad567ef6a423698"},{"url":"https://git.kernel.org/stable/c/c9961336aa5ff83092f23e33ee86666a9dbd1b2a"},{"url":"https://git.kernel.org/stable/c/a75d99f46bf21b45965ce39c5cfb3b8bb5ffb1aa"}],"tags":["cve.org"],"epss":0.00176,"epssPercentile":0.06637,"ingestedAt":"2026-10-16T19:46:24.400Z","slug":"CVE-2026-72400","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nseg6: validate SRH length before reading fixed fields\n\nseg6_validate_srh() reads fixed SRH fields such as srh->type and\nsrh->hdrlen before checking that the supplied length covers the fixed\nstruct ipv6_sr_hdr fields.\n\nThe BPF SEG6 encap path reaches this with a BPF program-supplied pointer\nand length: bpf_lwt_push_encap() and the SEG6 local BPF END_B6 and\nEND_B6_ENCAP actions call bpf_push_seg6_encap(), which forwards the\nlength to seg6_validate_srh() with no minimum-size guard.  A 2-byte SEG6\nencap header can therefore make the validator read srh->type at offset 2\nbeyond the caller-supplied buffer.\n\nReject lengths shorter than the fixed SRH at the top of\nseg6_validate_srh(), before any field is read.  This fixes the BPF helper\npath and keeps the common validator robust.\n\n## Affected\n\n- `Linux >= fe94cc290f535709d3c5ebd1e472dfd0aec7ee79 < 715eb12e453df752f1b4baaf972c3acff0ab9402`\n- `Linux >= fe94cc290f535709d3c5ebd1e472dfd0aec7ee79 < 7247d05c987c3eec4bb7c2306dbd77ecdf3b7c73`\n- `Linux >= fe94cc290f535709d3c5ebd1e472dfd0aec7ee79 < 071f1a38d7ddbadee29c09b9e3ee0ff3a61e6a0e`\n- `Linux >= fe94cc290f535709d3c5ebd1e472dfd0aec7ee79 < 804bb969f194c93497ba632b98343794c6367fdc`\n- `Linux >= fe94cc290f535709d3c5ebd1e472dfd0aec7ee79 < 0fc7069d39239978130c37ebceaec85c8948d3f1`\n- `Linux >= fe94cc290f535709d3c5ebd1e472dfd0aec7ee79 < 8dba7a94a269b88e500aafc25ad567ef6a423698`\n- `Linux >= fe94cc290f535709d3c5ebd1e472dfd0aec7ee79 < c9961336aa5ff83092f23e33ee86666a9dbd1b2a`\n- `Linux >= fe94cc290f535709d3c5ebd1e472dfd0aec7ee79 < a75d99f46bf21b45965ce39c5cfb3b8bb5ffb1aa`\n- `Linux 4.18`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"twilight","depthScore":43,"depthScoreParts":{"impact":42.9,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}