Vulnerability-Lookup

GHSA-4J29-HVP6-5V88

Vulnerability from github – Published: 2026-10-18 18:31 – Updated: 2026-10-18 18:31

Details

In the Linux kernel, the following vulnerability has been resolved:

bpf: Fix bounds check for skb-backed dynptrs

The skb_pointer_if_linear() function checks whether a memory region of length len starting at offset off into the skb is in the linear area, and returns a pointer to the region if so. The check currently subtracts between skb_headlen and offset of the check, and since skb_headlen is unsigned the subtraction can underflow. This causes the bounds check to spuriously pass and generate an arbitrary pointer of the form *(skb->data + off).

The only user of this helper is currently skb-backed BPF dynptr code. Returning the wrong pointer leads to the dynptr erroneously being backed with invalid memory.

Ensure the subtraction cannot underflow, and fail the check if it would. Use u64 arithmetic to also prevent overflow when calculating (skb_headlen(skb) - off) since off is unsigned.

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{
  "affected": [],
  "aliases": [
    "CVE-2026-98591"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-10-18T16:17:11Z",
    "severity": null
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Fix bounds check for skb-backed dynptrs\n\nThe skb_pointer_if_linear() function checks whether a\nmemory region of length len starting at offset off into\nthe skb is in the linear area, and returns a pointer to\nthe region if so. The check currently subtracts between\nskb_headlen and offset of the check, and since skb_headlen\nis unsigned the subtraction can underflow. This causes the\nbounds check to spuriously pass and generate an arbitrary\npointer of the form *(skb-\u003edata + off).\n\nThe only user of this helper is currently skb-backed BPF\ndynptr code. Returning the wrong pointer leads to the\ndynptr erroneously being backed with invalid memory.\n\nEnsure the subtraction cannot underflow, and fail the check if\nit would. Use u64 arithmetic to also prevent overflow when\ncalculating (skb_headlen(skb) - off) since off is unsigned.",
  "id": "GHSA-4j29-hvp6-5v88",
  "modified": "2026-10-18T18:31:55Z",
  "published": "2026-10-18T18:31:55Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-98591"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/1196903a27cac5c929c7517e987a8d159f20c5e5"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/1b923538598be768e9f2f258a77a083d00e0c78b"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/37877a24758068742fef687a7cf5362360dde1d1"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/39ffceaddb10753eac12785dba6ac0673860b4ac"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/ed6eec97b534979dcf28b40c389cee57bd6561d4"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}

CVE-2026-98591 (GCVE-0-2026-98591)

Vulnerability from cvelistv5 – Published: 2026-10-18 15:19 – Updated: 2026-10-19 09:22

Title

bpf: Fix bounds check for skb-backed dynptrs

Summary

In the Linux kernel, the following vulnerability has been resolved: bpf: Fix bounds check for skb-backed dynptrs The skb_pointer_if_linear() function checks whether a memory region of length len starting at offset off into the skb is in the linear area, and returns a pointer to the region if so. The check currently subtracts between skb_headlen and offset of the check, and since skb_headlen is unsigned the subtraction can underflow. This causes the bounds check to spuriously pass and generate an arbitrary pointer of the form *(skb->data + off). The only user of this helper is currently skb-backed BPF dynptr code. Returning the wrong pointer leads to the dynptr erroneously being backed with invalid memory. Ensure the subtraction cannot underflow, and fail the check if it would. Use u64 arithmetic to also prevent overflow when calculating (skb_headlen(skb) - off) since off is unsigned.

Severity

No CVSS data available.

Assigner

Linux CNA under the mitre root

CNA scorecard D 53/100 over 7018 records in the last 180 days details

References

5 references

URL	Tags
https://git.kernel.org/stable/c/1b923538598be768e…
https://git.kernel.org/stable/c/37877a24758068742…
https://git.kernel.org/stable/c/1196903a27cac5c92…
https://git.kernel.org/stable/c/39ffceaddb10753ea…
https://git.kernel.org/stable/c/ed6eec97b534979dc…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: 6f5a630d7c57cd79b1f526a95e757311e32d41e5 , < 1b923538598be768e9f2f258a77a083d00e0c78b (git) Affected: 6f5a630d7c57cd79b1f526a95e757311e32d41e5 , < 37877a24758068742fef687a7cf5362360dde1d1 (git) Affected: 6f5a630d7c57cd79b1f526a95e757311e32d41e5 , < 1196903a27cac5c929c7517e987a8d159f20c5e5 (git) Affected: 6f5a630d7c57cd79b1f526a95e757311e32d41e5 , < 39ffceaddb10753eac12785dba6ac0673860b4ac (git) Affected: 6f5a630d7c57cd79b1f526a95e757311e32d41e5 , < ed6eec97b534979dcf28b40c389cee57bd6561d4 (git)
Linux	Linux	Affected: 6.6 Unaffected: 0 , < 6.6 (semver) Unaffected: 6.6.158 , ≤ 6.6.* (semver) Unaffected: 6.12.112 , ≤ 6.12.* (semver) Unaffected: 6.18.55 , ≤ 6.18.* (semver) Unaffected: 7.2.9 , ≤ 7.2.* (semver) Unaffected: 7.3 , ≤ * (original_commit_for_fix)

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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "include/linux/skbuff.h"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
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              "versionType": "git"
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              "versionType": "git"
            },
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              "status": "affected",
              "version": "6f5a630d7c57cd79b1f526a95e757311e32d41e5",
              "versionType": "git"
            },
            {
              "lessThan": "39ffceaddb10753eac12785dba6ac0673860b4ac",
              "status": "affected",
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              "versionType": "git"
            },
            {
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              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "include/linux/skbuff.h"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.6"
            },
            {
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              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
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              "versionType": "semver"
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              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.112",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.55",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.9",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Fix bounds check for skb-backed dynptrs\n\nThe skb_pointer_if_linear() function checks whether a\nmemory region of length len starting at offset off into\nthe skb is in the linear area, and returns a pointer to\nthe region if so. The check currently subtracts between\nskb_headlen and offset of the check, and since skb_headlen\nis unsigned the subtraction can underflow. This causes the\nbounds check to spuriously pass and generate an arbitrary\npointer of the form *(skb-\u003edata + off).\n\nThe only user of this helper is currently skb-backed BPF\ndynptr code. Returning the wrong pointer leads to the\ndynptr erroneously being backed with invalid memory.\n\nEnsure the subtraction cannot underflow, and fail the check if\nit would. Use u64 arithmetic to also prevent overflow when\ncalculating (skb_headlen(skb) - off) since off is unsigned."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-19T09:22:16.758Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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        },
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      "title": "bpf: Fix bounds check for skb-backed dynptrs",
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  "cveMetadata": {
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-98591",
    "datePublished": "2026-10-18T15:19:03.567Z",
    "dateReserved": "2026-09-25T10:25:14.359Z",
    "dateUpdated": "2026-10-19T09:22:16.758Z",
    "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.

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