CVE-2026-72400 (GCVE-0-2026-72400)
Vulnerability from cvelistv5
Published
2026-08-15 05:56
Modified
2026-08-17 05:43
Severity ?
VLAI Severity ?
EPSS score ?
Summary
In the Linux kernel, the following vulnerability has been resolved:
seg6: validate SRH length before reading fixed fields
seg6_validate_srh() reads fixed SRH fields such as srh->type and
srh->hdrlen before checking that the supplied length covers the fixed
struct ipv6_sr_hdr fields.
The BPF SEG6 encap path reaches this with a BPF program-supplied pointer
and length: bpf_lwt_push_encap() and the SEG6 local BPF END_B6 and
END_B6_ENCAP actions call bpf_push_seg6_encap(), which forwards the
length to seg6_validate_srh() with no minimum-size guard. A 2-byte SEG6
encap header can therefore make the validator read srh->type at offset 2
beyond the caller-supplied buffer.
Reject lengths shorter than the fixed SRH at the top of
seg6_validate_srh(), before any field is read. This fixes the BPF helper
path and keeps the common validator robust.
References
Impacted products
| Vendor | Product | Version | ||
|---|---|---|---|---|
| Linux | Linux |
Version: fe94cc290f535709d3c5ebd1e472dfd0aec7ee79 Version: fe94cc290f535709d3c5ebd1e472dfd0aec7ee79 Version: fe94cc290f535709d3c5ebd1e472dfd0aec7ee79 Version: fe94cc290f535709d3c5ebd1e472dfd0aec7ee79 Version: fe94cc290f535709d3c5ebd1e472dfd0aec7ee79 Version: fe94cc290f535709d3c5ebd1e472dfd0aec7ee79 Version: fe94cc290f535709d3c5ebd1e472dfd0aec7ee79 Version: fe94cc290f535709d3c5ebd1e472dfd0aec7ee79 |
||
{
"containers": {
"cna": {
"affected": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"net/ipv6/seg6.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
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"status": "affected",
"version": "fe94cc290f535709d3c5ebd1e472dfd0aec7ee79",
"versionType": "git"
},
{
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"status": "affected",
"version": "fe94cc290f535709d3c5ebd1e472dfd0aec7ee79",
"versionType": "git"
},
{
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"status": "affected",
"version": "fe94cc290f535709d3c5ebd1e472dfd0aec7ee79",
"versionType": "git"
},
{
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"versionType": "git"
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{
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]
},
{
"defaultStatus": "affected",
"product": "Linux",
"programFiles": [
"net/ipv6/seg6.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "4.18"
},
{
"lessThan": "4.18",
"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "5.10.*",
"status": "unaffected",
"version": "5.10.261",
"versionType": "semver"
},
{
"lessThanOrEqual": "5.15.*",
"status": "unaffected",
"version": "5.15.212",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.1.*",
"status": "unaffected",
"version": "6.1.178",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.6.*",
"status": "unaffected",
"version": "6.6.145",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.12.*",
"status": "unaffected",
"version": "6.12.97",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.18.*",
"status": "unaffected",
"version": "6.18.40",
"versionType": "semver"
},
{
"lessThanOrEqual": "7.1.*",
"status": "unaffected",
"version": "7.1.5",
"versionType": "semver"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "7.2",
"versionType": "original_commit_for_fix"
}
]
}
],
"cpeApplicability": [
{
"nodes": [
{
"cpeMatch": [
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "5.10.261",
"versionStartIncluding": "4.18",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "5.15.212",
"versionStartIncluding": "4.18",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.18.40",
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"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "7.1.5",
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"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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"versionStartIncluding": "4.18",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
]
}
],
"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-\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."
}
],
"metrics": [
{
"cvssV3_1": {
"baseScore": 7.8,
"baseSeverity": "HIGH",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"version": "3.1"
},
"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-\u003etype 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."
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-08-17T05:43:42.988Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"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"
}
}
},
"cveMetadata": {
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2026-72400",
"datePublished": "2026-08-15T05:56:25.572Z",
"dateReserved": "2026-08-09T03:40:39.925Z",
"dateUpdated": "2026-08-17T05:43:42.988Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}
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Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
- Confirmed: The vulnerability is confirmed from an analyst perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
- Patched: This vulnerability was successfully patched by the user reporting the sighting.
- Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
- Not confirmed: The user expresses doubt about the veracity of the vulnerability.
- Not patched: This vulnerability was not successfully patched by the user reporting the sighting.
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