{"id":"CVE-2026-72400","summary":"seg6: validate SRH length before reading fixed fields","details":"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-\u003etype and\nsrh-\u003ehdrlen 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-\u003etype 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.","modified":"2026-08-18T04:17:19.128428140Z","published":"2026-08-15T05:56:25.572Z","database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/72xxx/CVE-2026-72400.json","cna_assigner":"Linux"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/071f1a38d7ddbadee29c09b9e3ee0ff3a61e6a0e"},{"type":"WEB","url":"https://git.kernel.org/stable/c/0fc7069d39239978130c37ebceaec85c8948d3f1"},{"type":"WEB","url":"https://git.kernel.org/stable/c/715eb12e453df752f1b4baaf972c3acff0ab9402"},{"type":"WEB","url":"https://git.kernel.org/stable/c/7247d05c987c3eec4bb7c2306dbd77ecdf3b7c73"},{"type":"WEB","url":"https://git.kernel.org/stable/c/804bb969f194c93497ba632b98343794c6367fdc"},{"type":"WEB","url":"https://git.kernel.org/stable/c/8dba7a94a269b88e500aafc25ad567ef6a423698"},{"type":"WEB","url":"https://git.kernel.org/stable/c/a75d99f46bf21b45965ce39c5cfb3b8bb5ffb1aa"},{"type":"WEB","url":"https://git.kernel.org/stable/c/c9961336aa5ff83092f23e33ee86666a9dbd1b2a"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/72xxx/CVE-2026-72400.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-72400"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"fe94cc290f535709d3c5ebd1e472dfd0aec7ee79"},{"fixed":"715eb12e453df752f1b4baaf972c3acff0ab9402"},{"fixed":"7247d05c987c3eec4bb7c2306dbd77ecdf3b7c73"},{"fixed":"071f1a38d7ddbadee29c09b9e3ee0ff3a61e6a0e"},{"fixed":"804bb969f194c93497ba632b98343794c6367fdc"},{"fixed":"0fc7069d39239978130c37ebceaec85c8948d3f1"},{"fixed":"8dba7a94a269b88e500aafc25ad567ef6a423698"},{"fixed":"c9961336aa5ff83092f23e33ee86666a9dbd1b2a"},{"fixed":"a75d99f46bf21b45965ce39c5cfb3b8bb5ffb1aa"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-72400.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"4.18.0"},{"fixed":"5.10.261"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.11.0"},{"fixed":"5.15.212"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.16.0"},{"fixed":"6.1.178"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.2.0"},{"fixed":"6.6.145"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.97"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.40"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.1.5"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-72400.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"}]}