Vulnerability-Lookup

GHSA-X2J2-WXW5-PJR8

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:

bpf: Guard conntrack opts error writes

The conntrack lookup and allocation kfuncs take an opts pointer together with an opts__sz argument. The verifier checks only the memory range described by opts__sz, but the wrappers unconditionally write opts->error whenever the internal lookup or allocation helper returns an error.

For an invalid size smaller than the end of opts->error, that write can land outside the verifier-checked range. Keep returning NULL for invalid arguments, but only report the error through opts->error when the supplied size includes the field.

This preserves error reporting for the supported 12-byte and 16-byte layouts, and for other invalid sizes that still include opts->error.

Severity

8.8 (High)


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

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{
  "affected": [],
  "aliases": [
    "CVE-2026-72423"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-08-15T06:22:16Z",
    "severity": "HIGH"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Guard conntrack opts error writes\n\nThe conntrack lookup and allocation kfuncs take an opts pointer\ntogether with an opts__sz argument. The verifier checks only the memory\nrange described by opts__sz, but the wrappers unconditionally write\nopts-\u003eerror whenever the internal lookup or allocation helper returns an\nerror.\n\nFor an invalid size smaller than the end of opts-\u003eerror, that write can\nland outside the verifier-checked range. Keep returning NULL for invalid\narguments, but only report the error through opts-\u003eerror when the\nsupplied size includes the field.\n\nThis preserves error reporting for the supported 12-byte and 16-byte\nlayouts, and for other invalid sizes that still include opts-\u003eerror.",
  "id": "GHSA-x2j2-wxw5-pjr8",
  "modified": "2026-08-17T06:33:29Z",
  "published": "2026-08-15T06:32:24Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-72423"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/6f6183a39533d727deaa5061cadae6dd9e6744d0"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/dd74c80203842a21b2ebb9f70d1260d9aa20fa05"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}

CVE-2026-72423 (GCVE-0-2026-72423)

Vulnerability from cvelistv5 – Published: 2026-08-15 05:56 – Updated: 2026-08-17 05:44

Title

bpf: Guard conntrack opts error writes

Summary

In the Linux kernel, the following vulnerability has been resolved: bpf: Guard conntrack opts error writes The conntrack lookup and allocation kfuncs take an opts pointer together with an opts__sz argument. The verifier checks only the memory range described by opts__sz, but the wrappers unconditionally write opts->error whenever the internal lookup or allocation helper returns an error. For an invalid size smaller than the end of opts->error, that write can land outside the verifier-checked range. Keep returning NULL for invalid arguments, but only report the error through opts->error when the supplied size includes the field. This preserves error reporting for the supported 12-byte and 16-byte layouts, and for other invalid sizes that still include opts->error.

Severity

8.8 (High)


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

Assigner

Linux mitre root

References

2 references

URL	Tags
https://git.kernel.org/stable/c/dd74c80203842a21b…
https://git.kernel.org/stable/c/6f6183a39533d727d…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: b4c2b9593a1c4c3a718370e34af28e817fd5e5c6 , < dd74c80203842a21b2ebb9f70d1260d9aa20fa05 (git) Affected: b4c2b9593a1c4c3a718370e34af28e817fd5e5c6 , < 6f6183a39533d727deaa5061cadae6dd9e6744d0 (git)
Linux	Linux	Affected: 5.18 Unaffected: 0 , < 5.18 (semver) Unaffected: 7.1.5 , ≤ 7.1.* (semver) Unaffected: 7.2 , ≤ * (original_commit_for_fix)

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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/netfilter/nf_conntrack_bpf.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "dd74c80203842a21b2ebb9f70d1260d9aa20fa05",
              "status": "affected",
              "version": "b4c2b9593a1c4c3a718370e34af28e817fd5e5c6",
              "versionType": "git"
            },
            {
              "lessThan": "6f6183a39533d727deaa5061cadae6dd9e6744d0",
              "status": "affected",
              "version": "b4c2b9593a1c4c3a718370e34af28e817fd5e5c6",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "net/netfilter/nf_conntrack_bpf.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "5.18"
            },
            {
              "lessThan": "5.18",
              "status": "unaffected",
              "version": "0",
              "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": "7.1.5",
                  "versionStartIncluding": "5.18",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2",
                  "versionStartIncluding": "5.18",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Guard conntrack opts error writes\n\nThe conntrack lookup and allocation kfuncs take an opts pointer\ntogether with an opts__sz argument. The verifier checks only the memory\nrange described by opts__sz, but the wrappers unconditionally write\nopts-\u003eerror whenever the internal lookup or allocation helper returns an\nerror.\n\nFor an invalid size smaller than the end of opts-\u003eerror, that write can\nland outside the verifier-checked range. Keep returning NULL for invalid\narguments, but only report the error through opts-\u003eerror when the\nsupplied size includes the field.\n\nThis preserves error reporting for the supported 12-byte and 16-byte\nlayouts, and for other invalid sizes that still include opts-\u003eerror."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 8.8,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - Exploitation requires loading and attaching a BPF XDP or TC program that calls the conntrack kfuncs via the bpf() syscall; per kernel CNA guidance BPF/netfilter paths are Local even when programs later run on network packets.\nAC:L - An attacker reliably triggers the bug by calling bpf_xdp_ct_lookup/alloc or bpf_skb_ct_lookup/alloc with opts__sz smaller than the error field (e.g. 4); the helper returns EINVAL and the wrapper performs the out-of-bounds write with no races or attacker-uncontrollable conditions.\nPR:L - Loading BPF_PROG_TYPE_XDP or BPF_PROG_TYPE_SCHED_CLS programs requires CAP_NET_ADMIN, which unprivileged users can obtain inside user/network namespaces (unshare -Urn) on typical Linux deployments without init-namespace root.\nUI:N - No victim interaction is required; the attacker loads their own BPF program and invokes the kfunc with a small opts__sz to trigger the out-of-bounds write on demand.\nS:C - Corrupting kernel memory via a verifier-bypassing BPF stack write from a user/network namespace can cross the namespace/container trust boundary to compromise the host kernel, exceeding the attacker\u0027s original security scope.\nC:H - The bug is a controlled 4-byte out-of-bounds write past the verifier-approved opts buffer on the BPF stack, a memory-corruption primitive that can be leveraged for arbitrary kernel memory disclosure.\nI:H - Writing opts-\u003eerror outside the verifier-checked range corrupts adjacent BPF stack slots with attacker-influenced errno values, enabling heap/stack grooming and control-flow hijacking toward arbitrary kernel code execution.\nA:H - Corrupting BPF stack memory outside verifier bounds can cause immediate kernel oops/panic or be used in a repeatable crash/DoS loop when the attached XDP/TC program runs on incoming traffic."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-17T05:44:03.898Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/dd74c80203842a21b2ebb9f70d1260d9aa20fa05"
        },
        {
          "url": "https://git.kernel.org/stable/c/6f6183a39533d727deaa5061cadae6dd9e6744d0"
        }
      ],
      "title": "bpf: Guard conntrack opts error writes",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-72423",
    "datePublished": "2026-08-15T05:56:41.711Z",
    "dateReserved": "2026-08-09T03:40:39.928Z",
    "dateUpdated": "2026-08-17T05:44:03.898Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "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-X2J2-WXW5-PJR8

CVE-2026-72423 (GCVE-0-2026-72423)

Tags

Sightings

Nomenclature