{ "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" } } } }