netfilter: xt_multiport: validate range encoding in checkentry

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Summary

CVECVE-2026-31681
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-04-25 09:16:01 UTC
Updated2026-06-01 17:16:55 UTC
DescriptionIn 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.

Risk And Classification

Primary CVSS: v3.1 5.5 MEDIUM from [email protected]

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

EPSS: 0.000180000 probability, percentile 0.046080000 (date 2026-04-27)

Problem Types: NVD-CWE-noinfo

CVSS v3.1 Breakdown

Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

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

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Operating System Linux Linux Kernel All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected a89ecb6a2ef732d04058d87801e2b6bd7e5c7089 8c5bf8f5b478f569191c4a7982de7cd5f5f73c1a git Not specified
CNA Linux Linux affected a89ecb6a2ef732d04058d87801e2b6bd7e5c7089 c9749f6232c845e31c21d4cc72200211df15d8a2 git Not specified
CNA Linux Linux affected a89ecb6a2ef732d04058d87801e2b6bd7e5c7089 b67d638cbee9975c765feb45c126e96ed11ec802 git Not specified
CNA Linux Linux affected a89ecb6a2ef732d04058d87801e2b6bd7e5c7089 36bf0d98e180a7c384c8d8a59b0d2d4b80e5eb16 git Not specified
CNA Linux Linux affected a89ecb6a2ef732d04058d87801e2b6bd7e5c7089 aec14808271f2bf2b656de6ff12dfe73c5fd3b67 git Not specified
CNA Linux Linux affected a89ecb6a2ef732d04058d87801e2b6bd7e5c7089 8368ce8eb01f0b91111d814703696e780d0ef12f git Not specified
CNA Linux Linux affected a89ecb6a2ef732d04058d87801e2b6bd7e5c7089 1e4baa853f1cc4227e04f52d6860524707cfb294 git Not specified
CNA Linux Linux affected a89ecb6a2ef732d04058d87801e2b6bd7e5c7089 ff64c5bfef12461df8450e0f50bb693b5269c720 git Not specified
CNA Linux Linux affected 2.6.17 Not specified
CNA Linux Linux unaffected 2.6.17 semver Not specified
CNA Linux Linux unaffected 5.10.258 5.10.* semver Not specified
CNA Linux Linux unaffected 5.15.209 5.15.* semver Not specified
CNA Linux Linux unaffected 6.1.175 6.1.* semver Not specified
CNA Linux Linux unaffected 6.6.136 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.83 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.24 6.18.* semver Not specified
CNA Linux Linux unaffected 6.19.14 6.19.* semver Not specified
CNA Linux Linux unaffected 7.0 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/8368ce8eb01f0b91111d814703696e780d0ef12f 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/aec14808271f2bf2b656de6ff12dfe73c5fd3b67 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/36bf0d98e180a7c384c8d8a59b0d2d4b80e5eb16 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/b67d638cbee9975c765feb45c126e96ed11ec802 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/c9749f6232c845e31c21d4cc72200211df15d8a2 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/1e4baa853f1cc4227e04f52d6860524707cfb294 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/8c5bf8f5b478f569191c4a7982de7cd5f5f73c1a 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/ff64c5bfef12461df8450e0f50bb693b5269c720 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
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