System crash via malformed multiport range encoding
Published Apr 25, 2026 · Updated Apr 25, 2026
Out-of-bounds read in Linux Kernel allows local users to crash the system by installing a malformed netfilter multiport v1 rule. The xt_multiport checkentry path accepts a range-start marker in the last ports[] slot or consecutive range starts, so ports_match_v1() consumes an element beyond the validated array. Exploitation requires local low-privileged access and permission to install netfilter rules; the bounded consequence is a kernel crash and service interruption.
Summary
What happened
Out-of-bounds read in Linux Kernel allows local users to crash the system by installing a malformed netfilter multiport v1 rule. The xt_multiport checkentry path accepts a range-start marker in the last ports[] slot or consecutive range starts, so ports_match_v1() consumes an element beyond the validated array. Exploitation requires local low-privileged access and permission to install netfilter rules; the bounded consequence is a kernel crash and service interruption.
The record
- CVE
- CVE-2026-31681
- Published
- Apr 25, 2026
- Updated
- Apr 25, 2026
- Vendor
- The Linux Kernel Organization
- Product
- Linux Kernel
- Classifications
- T1499
- Attack vector
- local
- Privileges
- authenticated
Timeline
How it unfolded
- Apr 25, 2026CVE publishedPublication date reported by the CVE source.
- Apr 25, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
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- Affected versionversion=2.6.17
- Affected versionversion=a89ecb6a2ef732d04058d87801e2b6bd7e5c7089 <1e4baa853f1cc4227e04f52d6860524707cfb294
- Affected versionversion=a89ecb6a2ef732d04058d87801e2b6bd7e5c7089 <8368ce8eb01f0b91111d814703696e780d0ef12f
- Affected versionversion=a89ecb6a2ef732d04058d87801e2b6bd7e5c7089 <aec14808271f2bf2b656de6ff12dfe73c5fd3b67
- Affected versionversion=a89ecb6a2ef732d04058d87801e2b6bd7e5c7089 <ff64c5bfef12461df8450e0f50bb693b5269c720
What conditions does exploitation require?
What is affected?
Published CVSS scores
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Attacks
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Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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Your stack
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