Vulnerability-Lookup

GHSA-X2WV-639G-PV5Q

Vulnerability from github – Published: 2026-08-15 06:32 – Updated: 2026-08-17 06:33

Details

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.

Severity

7.8 (High)


                  
                    CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

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{
  "affected": [],
  "aliases": [
    "CVE-2026-72400"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-08-15T06:22:13Z",
    "severity": "HIGH"
  },
  "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.",
  "id": "GHSA-x2wv-639g-pv5q",
  "modified": "2026-08-17T06:33:27Z",
  "published": "2026-08-15T06:32:23Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-72400"
    },
    {
      "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"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}

CVE-2026-72400 (GCVE-0-2026-72400)

Vulnerability from cvelistv5 – Published: 2026-08-15 05:56 – Updated: 2026-08-17 05:43

Title

seg6: validate SRH length before reading fixed fields

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.

Severity

7.8 (High)


                        
                          CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Assigner

Linux mitre root

References

8 references

URL	Tags
https://git.kernel.org/stable/c/715eb12e453df752f…
https://git.kernel.org/stable/c/7247d05c987c3eec4…
https://git.kernel.org/stable/c/071f1a38d7ddbadee…
https://git.kernel.org/stable/c/804bb969f194c9349…
https://git.kernel.org/stable/c/0fc7069d392399781…
https://git.kernel.org/stable/c/8dba7a94a269b88e5…
https://git.kernel.org/stable/c/c9961336aa5ff8309…
https://git.kernel.org/stable/c/a75d99f46bf21b459…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: fe94cc290f535709d3c5ebd1e472dfd0aec7ee79 , < 715eb12e453df752f1b4baaf972c3acff0ab9402 (git) Affected: fe94cc290f535709d3c5ebd1e472dfd0aec7ee79 , < 7247d05c987c3eec4bb7c2306dbd77ecdf3b7c73 (git) Affected: fe94cc290f535709d3c5ebd1e472dfd0aec7ee79 , < 071f1a38d7ddbadee29c09b9e3ee0ff3a61e6a0e (git) Affected: fe94cc290f535709d3c5ebd1e472dfd0aec7ee79 , < 804bb969f194c93497ba632b98343794c6367fdc (git) Affected: fe94cc290f535709d3c5ebd1e472dfd0aec7ee79 , < 0fc7069d39239978130c37ebceaec85c8948d3f1 (git) Affected: fe94cc290f535709d3c5ebd1e472dfd0aec7ee79 , < 8dba7a94a269b88e500aafc25ad567ef6a423698 (git) Affected: fe94cc290f535709d3c5ebd1e472dfd0aec7ee79 , < c9961336aa5ff83092f23e33ee86666a9dbd1b2a (git) Affected: fe94cc290f535709d3c5ebd1e472dfd0aec7ee79 , < a75d99f46bf21b45965ce39c5cfb3b8bb5ffb1aa (git)
Linux	Linux	Affected: 4.18 Unaffected: 0 , < 4.18 (semver) Unaffected: 5.10.261 , ≤ 5.10.* (semver) Unaffected: 5.15.212 , ≤ 5.15.* (semver) Unaffected: 6.1.178 , ≤ 6.1.* (semver) Unaffected: 6.6.145 , ≤ 6.6.* (semver) Unaffected: 6.12.97 , ≤ 6.12.* (semver) Unaffected: 6.18.40 , ≤ 6.18.* (semver) Unaffected: 7.1.5 , ≤ 7.1.* (semver) Unaffected: 7.2 , ≤ * (original_commit_for_fix)

Show details on NVD website

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{
  "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",
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              "version": "4.18"
            },
            {
              "lessThan": "4.18",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
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            {
              "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"
            },
            {
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              "status": "unaffected",
              "version": "6.6.145",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.97",
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            {
              "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": [
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                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "5.10.261",
                  "versionStartIncluding": "4.18",
                  "vulnerable": true
                },
                {
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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:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2",
                  "versionStartIncluding": "4.18",
                  "vulnerable": true
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              "operator": "OR"
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        }
      ],
      "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."
        }
      ],
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            "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"
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        {
          "url": "https://git.kernel.org/stable/c/a75d99f46bf21b45965ce39c5cfb3b8bb5ffb1aa"
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      ],
      "title": "seg6: validate SRH length before reading fixed fields",
      "x_generator": {
        "engine": "bippy-1.2.0"
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    "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"
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  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.

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GHSA-X2WV-639G-PV5Q

CVE-2026-72400 (GCVE-0-2026-72400)

Tags

Sightings

Nomenclature