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

Vulnerability from cvelistv5 – Published: 2026-04-25 08:46 – Updated: 2026-04-27 13:57
VLAI?
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
References
Impacted products
Vendor Product Version
Linux Linux Affected: a89ecb6a2ef732d04058d87801e2b6bd7e5c7089 , < 36bf0d98e180a7c384c8d8a59b0d2d4b80e5eb16 (git)
Affected: a89ecb6a2ef732d04058d87801e2b6bd7e5c7089 , < aec14808271f2bf2b656de6ff12dfe73c5fd3b67 (git)
Affected: a89ecb6a2ef732d04058d87801e2b6bd7e5c7089 , < 8368ce8eb01f0b91111d814703696e780d0ef12f (git)
Affected: a89ecb6a2ef732d04058d87801e2b6bd7e5c7089 , < 1e4baa853f1cc4227e04f52d6860524707cfb294 (git)
Affected: a89ecb6a2ef732d04058d87801e2b6bd7e5c7089 , < ff64c5bfef12461df8450e0f50bb693b5269c720 (git)
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    Linux 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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{
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          "programFiles": [
            "net/netfilter/xt_multiport.c"
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          "value": "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."
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        "shortName": "Linux"
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    "datePublished": "2026-04-25T08:46:57.995Z",
    "dateReserved": "2026-03-09T15:48:24.130Z",
    "dateUpdated": "2026-04-27T13:57:13.951Z",
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  }
}


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  • 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.
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  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.



Detection rules are retrieved from Rulezet.