{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-72400","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","state":"PUBLISHED","assignerShortName":"Linux","dateReserved":"2026-08-09T03:40:39.925Z","datePublished":"2026-08-15T05:56:25.572Z","dateUpdated":"2026-08-17T05:43:42.988Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-08-17T05:43:42.988Z"},"descriptions":[{"lang":"en","value":"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 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."}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","baseScore":7.8,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:L - Exploitation requires loading BPF LWT SEG6 programs and attaching SRv6 routes via bpf() and RTNETLINK; the OOB read is triggered through bpf_lwt_push_encap/bpf_lwt_seg6_action helpers, not by remote IPv6 packet parsing alone.\nAC:L - An attacker with route/BPF setup privileges can deterministically call bpf_push_seg6_encap() or bpf_lwt_seg6_action(END_B6/END_B6_ENCAP) with a 2-byte buffer, immediately forcing seg6_validate_srh() to read fixed SRH fields past the buffer end.\nPR:L - Loading BPF_PROG_TYPE_LWT_IN/LWT_SEG6LOCAL and installing SRv6 LWT routes requires CAP_NET_ADMIN, obtainable by unprivileged users inside user/network namespaces (unshare -Urn), not only init-namespace root.\nUI:N - No victim interaction is required; triggering the bug needs only attacker-controlled BPF execution during SRv6/LWT packet processing after the attacker configures routes and programs.\nS:U - Impact is confined to kernel memory safety within the same host security boundary; there is no VM escape, sandbox breakout, or cross-authority scope change beyond standard local kernel compromise.\nC:H - seg6_validate_srh() performs out-of-bounds reads of SRH header bytes (e.g., srh->type at offset 2) beyond the attacker-supplied length, disclosing adjacent kernel/BPF stack memory that may include pointers and sensitive metadata.\nI:H - Kernel out-of-bounds reads in this validation path constitute memory-safety corruption that can be chained with disclosed pointers and heap/stack layout control from BPF context to obtain arbitrary write or code-execution primitives.\nA:H - Undersized SRH buffers can cause seg6_validate_srh() to read past mapped BPF/kernel memory and trigger kernel faults, oops, or panic on SRv6 routers processing attacker-driven BPF SEG6 encap traffic."}]}],"affected":[{"product":"Linux","vendor":"Linux","defaultStatus":"unaffected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/ipv6/seg6.c"],"versions":[{"version":"fe94cc290f535709d3c5ebd1e472dfd0aec7ee79","lessThan":"715eb12e453df752f1b4baaf972c3acff0ab9402","status":"affected","versionType":"git"},{"version":"fe94cc290f535709d3c5ebd1e472dfd0aec7ee79","lessThan":"7247d05c987c3eec4bb7c2306dbd77ecdf3b7c73","status":"affected","versionType":"git"},{"version":"fe94cc290f535709d3c5ebd1e472dfd0aec7ee79","lessThan":"071f1a38d7ddbadee29c09b9e3ee0ff3a61e6a0e","status":"affected","versionType":"git"},{"version":"fe94cc290f535709d3c5ebd1e472dfd0aec7ee79","lessThan":"804bb969f194c93497ba632b98343794c6367fdc","status":"affected","versionType":"git"},{"version":"fe94cc290f535709d3c5ebd1e472dfd0aec7ee79","lessThan":"0fc7069d39239978130c37ebceaec85c8948d3f1","status":"affected","versionType":"git"},{"version":"fe94cc290f535709d3c5ebd1e472dfd0aec7ee79","lessThan":"8dba7a94a269b88e500aafc25ad567ef6a423698","status":"affected","versionType":"git"},{"version":"fe94cc290f535709d3c5ebd1e472dfd0aec7ee79","lessThan":"c9961336aa5ff83092f23e33ee86666a9dbd1b2a","status":"affected","versionType":"git"},{"version":"fe94cc290f535709d3c5ebd1e472dfd0aec7ee79","lessThan":"a75d99f46bf21b45965ce39c5cfb3b8bb5ffb1aa","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/ipv6/seg6.c"],"versions":[{"version":"4.18","status":"affected"},{"version":"0","lessThan":"4.18","status":"unaffected","versionType":"semver"},{"version":"5.10.261","lessThanOrEqual":"5.10.*","status":"unaffected","versionType":"semver"},{"version":"5.15.212","lessThanOrEqual":"5.15.*","status":"unaffected","versionType":"semver"},{"version":"6.1.178","lessThanOrEqual":"6.1.*","status":"unaffected","versionType":"semver"},{"version":"6.6.145","lessThanOrEqual":"6.6.*","status":"unaffected","versionType":"semver"},{"version":"6.12.97","lessThanOrEqual":"6.12.*","status":"unaffected","versionType":"semver"},{"version":"6.18.40","lessThanOrEqual":"6.18.*","status":"unaffected","versionType":"semver"},{"version":"7.1.5","lessThanOrEqual":"7.1.*","status":"unaffected","versionType":"semver"},{"version":"7.2","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":"4.18","versionEndExcluding":"5.10.261"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.18","versionEndExcluding":"5.15.212"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.18","versionEndExcluding":"6.1.178"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.18","versionEndExcluding":"6.6.145"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.18","versionEndExcluding":"6.12.97"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.18","versionEndExcluding":"6.18.40"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.18","versionEndExcluding":"7.1.5"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.18","versionEndExcluding":"7.2"}]}]}],"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"}],"title":"seg6: validate SRH length before reading fixed fields","x_generator":{"engine":"bippy-1.2.0"}}}}