Vulnerability-Lookup

GHSA-F822-MPGR-7CQX

Vulnerability from github – Published: 2026-04-25 09:30 – Updated: 2026-05-06 21:31

Details

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

netfilter: xt_multiport: validate range encoding in checkentry

ports_match_v1() treats any non-zero pflags entry as the start of a port range and unconditionally consumes the next ports[] element as the range end.

The checkentry path currently validates protocol, flags and count, but it does not validate the range encoding itself. As a result, malformed rules can mark the last slot as a range start or place two range starts back to back, leaving ports_match_v1() to step past the last valid ports[] element while interpreting the rule.

Reject malformed multiport v1 rules in checkentry by validating that each range start has a following element and that the following element is not itself marked as another range start.

Severity ?

5.5 (Medium)


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

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{
  "affected": [],
  "aliases": [
    "CVE-2026-31681"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-04-25T09:16:01Z",
    "severity": "MODERATE"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: xt_multiport: validate range encoding in checkentry\n\nports_match_v1() treats any non-zero pflags entry as the start of a\nport range and unconditionally consumes the next ports[] element as\nthe range end.\n\nThe checkentry path currently validates protocol, flags and count, but\nit does not validate the range encoding itself. As a result, malformed\nrules can mark the last slot as a range start or place two range starts\nback to back, leaving ports_match_v1() to step past the last valid\nports[] element while interpreting the rule.\n\nReject malformed multiport v1 rules in checkentry by validating that\neach range start has a following element and that the following element\nis not itself marked as another range start.",
  "id": "GHSA-f822-mpgr-7cqx",
  "modified": "2026-05-06T21:31:30Z",
  "published": "2026-04-25T09:30:28Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-31681"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/1e4baa853f1cc4227e04f52d6860524707cfb294"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/36bf0d98e180a7c384c8d8a59b0d2d4b80e5eb16"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/8368ce8eb01f0b91111d814703696e780d0ef12f"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/aec14808271f2bf2b656de6ff12dfe73c5fd3b67"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/ff64c5bfef12461df8450e0f50bb693b5269c720"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ]
}

CVE-2026-31681 (GCVE-0-2026-31681)

Vulnerability from cvelistv5 – Published: 2026-04-25 08:46 – Updated: 2026-04-27 13:57

Title

netfilter: xt_multiport: validate range encoding in checkentry

Summary

In the Linux kernel, the following vulnerability has been resolved: netfilter: xt_multiport: validate range encoding in checkentry ports_match_v1() treats any non-zero pflags entry as the start of a port range and unconditionally consumes the next ports[] element as the range end. The checkentry path currently validates protocol, flags and count, but it does not validate the range encoding itself. As a result, malformed rules can mark the last slot as a range start or place two range starts back to back, leaving ports_match_v1() to step past the last valid ports[] element while interpreting the rule. Reject malformed multiport v1 rules in checkentry by validating that each range start has a following element and that the following element is not itself marked as another range start.

Severity ?

No CVSS data available.

Assigner

Linux

References

URL

Tags

	https://git.kernel.org/stable/c/36bf0d98e180a7c38…
	https://git.kernel.org/stable/c/aec14808271f2bf2b…
	https://git.kernel.org/stable/c/8368ce8eb01f0b911…
	https://git.kernel.org/stable/c/1e4baa853f1cc4227…
	https://git.kernel.org/stable/c/ff64c5bfef12461df…

Impacted products

Vendor

Product

Version

Linux

Affected: a89ecb6a2ef732d04058d87801e2b6bd7e5c7089 , < 36bf0d98e180a7c384c8d8a59b0d2d4b80e5eb16 (git)
Affected: a89ecb6a2ef732d04058d87801e2b6bd7e5c7089 , < aec14808271f2bf2b656de6ff12dfe73c5fd3b67 (git)
Affected: a89ecb6a2ef732d04058d87801e2b6bd7e5c7089 , < 8368ce8eb01f0b91111d814703696e780d0ef12f (git)
Affected: a89ecb6a2ef732d04058d87801e2b6bd7e5c7089 , < 1e4baa853f1cc4227e04f52d6860524707cfb294 (git)
Affected: a89ecb6a2ef732d04058d87801e2b6bd7e5c7089 , < ff64c5bfef12461df8450e0f50bb693b5269c720 (git)

Linux

Affected: 2.6.17
Unaffected: 0 , < 2.6.17 (semver)
Unaffected: 6.6.136 , ≤ 6.6.* (semver)
Unaffected: 6.12.83 , ≤ 6.12.* (semver)
Unaffected: 6.18.24 , ≤ 6.18.* (semver)
Unaffected: 6.19.14 , ≤ 6.19.* (semver)
Unaffected: 7.0 , ≤ * (original_commit_for_fix)

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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/netfilter/xt_multiport.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
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              "versionType": "git"
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              "versionType": "git"
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          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
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          ],
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          "vendor": "Linux",
          "versions": [
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              "version": "2.6.17"
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              "status": "unaffected",
              "version": "0",
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              "status": "unaffected",
              "version": "6.12.83",
              "versionType": "semver"
            },
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              "status": "unaffected",
              "version": "6.18.24",
              "versionType": "semver"
            },
            {
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              "status": "unaffected",
              "version": "6.19.14",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.0",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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        }
      ],
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        "dateUpdated": "2026-04-27T13:57:13.951Z",
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        {
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      "title": "netfilter: xt_multiport: validate range encoding in checkentry",
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    "cveId": "CVE-2026-31681",
    "datePublished": "2026-04-25T08:46:57.995Z",
    "dateReserved": "2026-03-09T15:48:24.130Z",
    "dateUpdated": "2026-04-27T13:57:13.951Z",
    "state": "PUBLISHED"
  },
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}

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.

Action not permitted

GHSA-F822-MPGR-7CQX

CVE-2026-31681 (GCVE-0-2026-31681)

Tags

Sightings

Nomenclature