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.
Advisories

No advisories yet.

Fixes

Solution

No solution given by the vendor.


Workaround

No workaround given by the vendor.

History

Mon, 27 Apr 2026 14:15:00 +0000


Mon, 27 Apr 2026 12:15:00 +0000

Type Values Removed Values Added
Weaknesses CWE-1285
References
Metrics threat_severity

None

cvssV3_1

{'score': 5.5, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H'}

threat_severity

Moderate


Sat, 25 Apr 2026 09:00:00 +0000

Type Values Removed Values Added
Description 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.
Title netfilter: xt_multiport: validate range encoding in checkentry
First Time appeared Linux
Linux linux Kernel
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
Vendors & Products Linux
Linux linux Kernel
References

Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: Linux

Published:

Updated: 2026-04-27T13:57:13.951Z

Reserved: 2026-03-09T15:48:24.130Z

Link: CVE-2026-31681

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Awaiting Analysis

Published: 2026-04-25T09:16:01.800

Modified: 2026-04-27T18:32:22.917

Link: CVE-2026-31681

cve-icon Redhat

Severity : Moderate

Publid Date: 2026-04-25T00:00:00Z

Links: CVE-2026-31681 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2026-04-27T20:45:12Z

Weaknesses