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

Vulnerability from cvelistv5 – Published: 2026-08-15 05:56 – Updated: 2026-10-16 18:55
VLAI
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
SSVC
Exploitation: none Automatable: no Technical Impact: total
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-10-16 18:49 UTC
Assigner
Linux CNA under the mitre root
CNA scorecard D 53/100 over 6992 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: b4c2b9593a1c4c3a718370e34af28e817fd5e5c6 , < 453f4f1e90de55b6bc297936031b68bef93f2e28 (git)
Affected: b4c2b9593a1c4c3a718370e34af28e817fd5e5c6 , < dd74c80203842a21b2ebb9f70d1260d9aa20fa05 (git)
Affected: b4c2b9593a1c4c3a718370e34af28e817fd5e5c6 , < 6f6183a39533d727deaa5061cadae6dd9e6744d0 (git)
guessed Create a notification for this product.
Linux Linux Affected: 5.18
Unaffected: 0 , < 5.18 (semver)
Unaffected: 6.18.57 , ≤ 6.18.* (semver)
Unaffected: 7.1.5 , ≤ 7.1.* (semver)
Unaffected: 7.2 , ≤ * (original_commit_for_fix)
guessed Create a notification for this product.
Show details on NVD website
To clipboard 

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-72423",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "total"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-10-16T18:49:41.501757Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-10-16T18:55:23.252Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "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": "453f4f1e90de55b6bc297936031b68bef93f2e28",
              "status": "affected",
              "version": "b4c2b9593a1c4c3a718370e34af28e817fd5e5c6",
              "versionType": "git"
            },
            {
              "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": "6.18.*",
              "status": "unaffected",
              "version": "6.18.57",
              "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": "6.18.57",
                  "versionStartIncluding": "5.18",
                  "vulnerable": true
                },
                {
                  "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": "2026-10-15T10:08:41.568Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/453f4f1e90de55b6bc297936031b68bef93f2e28"
        },
        {
          "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": "2026-10-16T18:55:23.252Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2026-72423",
      "date": "2026-10-20",
      "epss": "0.00173",
      "percentile": "0.06387"
    },
    "microsoft_vex": {
      "current_release_date": "2026-09-24T02:06:11.000Z",
      "cve": "CVE-2026-72423",
      "id": "msrc_CVE-2026-72423",
      "initial_release_date": "2026-08-23T15:01:18.000Z",
      "product_status:known_affected": "3",
      "source": "Microsoft CSAF VEX",
      "status": "final",
      "title": "bpf: Guard conntrack opts error writes",
      "url": "https://msrc.microsoft.com/csaf/vex/2026/msrc_cve-2026-72423.json",
      "version": "4"
    },
    "nvd": {
      "cve": {
        "affected": [
          {
            "affectedData": [
              {
                "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": "453f4f1e90de55b6bc297936031b68bef93f2e28",
                    "status": "affected",
                    "version": "b4c2b9593a1c4c3a718370e34af28e817fd5e5c6",
                    "versionType": "git"
                  },
                  {
                    "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": "6.18.*",
                    "status": "unaffected",
                    "version": "6.18.57",
                    "versionType": "semver"
                  },
                  {
                    "lessThanOrEqual": "7.1.*",
                    "status": "unaffected",
                    "version": "7.1.5",
                    "versionType": "semver"
                  },
                  {
                    "lessThanOrEqual": "*",
                    "status": "unaffected",
                    "version": "7.2",
                    "versionType": "original_commit_for_fix"
                  }
                ]
              }
            ],
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
          }
        ],
        "cveTags": [],
        "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."
          }
        ],
        "id": "CVE-2026-72423",
        "lastModified": "2026-10-16T19:17:29.780",
        "metrics": {
          "cvssMetricV31": [
            {
              "cvssData": {
                "attackComplexity": "LOW",
                "attackVector": "LOCAL",
                "availabilityImpact": "HIGH",
                "baseScore": 8.8,
                "baseSeverity": "HIGH",
                "confidentialityImpact": "HIGH",
                "integrityImpact": "HIGH",
                "privilegesRequired": "LOW",
                "scope": "CHANGED",
                "userInteraction": "NONE",
                "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H",
                "version": "3.1"
              },
              "exploitabilityScore": 2.0,
              "impactScore": 6.0,
              "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
              "type": "Secondary"
            }
          ],
          "ssvcV203": [
            {
              "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
              "ssvcData": {
                "id": "CVE-2026-72423",
                "options": [
                  {
                    "exploitation": "none"
                  },
                  {
                    "automatable": "no"
                  },
                  {
                    "technicalImpact": "total"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-10-16T18:49:41.501757Z",
                "version": "2.0.3"
              }
            }
          ]
        },
        "published": "2026-08-15T06:22:16.117",
        "references": [
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "url": "https://git.kernel.org/stable/c/453f4f1e90de55b6bc297936031b68bef93f2e28"
          },
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "url": "https://git.kernel.org/stable/c/6f6183a39533d727deaa5061cadae6dd9e6744d0"
          },
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "url": "https://git.kernel.org/stable/c/dd74c80203842a21b2ebb9f70d1260d9aa20fa05"
          }
        ],
        "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "vulnStatus": "Received"
      }
    },
    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-10-16T23:14:39+00:00",
      "cve": "CVE-2026-72423",
      "id": "CVE-2026-72423",
      "initial_release_date": "2026-08-15T00:00:00+00:00",
      "product_status:known_affected": "108",
      "product_status:known_not_affected": "167",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: bpf: Guard conntrack opts error writes",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-72423.json",
      "version": "3"
    }
  }
}



Log in or create an account to share your comment.




Tags
Taxonomy of the tags.




Drag nodes to arrange them. Double-click a related vulnerability to open it, or a source to visit its link. The Physics button on the left tunes the layout and the simulation; the legend at the bottom left hides or shows nodes by kind and by sighting type.

Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

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.
Vulnerability timeline

Sightings and recorded dates, grouped by day · UTC

JSON

Loading timeline…




    Related by attack behaviour

    Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.