Conntrack cleanup hang via retained fraglist references
Published Jan 31, 2026 · Updated Jan 31, 2026
Denial of service in Linux Kernel 6.18 through 6.18.5 allows local users to hang conntrack cleanup via fragmented traffic. Reassembled socket buffers enter the deferred-free list while frag_list members retain nf_conn references because cleanup does not traverse the fraglist. Reproduction requires a network namespace that emits fragmented traffic; the resulting reference leak blocks conntrack cleanup and module removal.
Summary
What happened
Denial of service in Linux Kernel 6.18 through 6.18.5 allows local users to hang conntrack cleanup via fragmented traffic. Reassembled socket buffers enter the deferred-free list while frag_list members retain nf_conn references because cleanup does not traverse the fraglist. Reproduction requires a network namespace that emits fragmented traffic; the resulting reference leak blocks conntrack cleanup and module removal.
The record
- CVE
- CVE-2026-23016
- Published
- Jan 31, 2026
- Updated
- Jan 31, 2026
- Vendor
- The Linux Kernel Organization
- Product
- Linux Kernel
- Classifications
- T1499.004
- Attack vector
- local
- Privileges
- authenticated
Timeline
How it unfolded
- Jan 31, 2026CVE publishedPublication date reported by the CVE source.
- Jan 31, 2026Record updatedLatest update available in the CVE record.
Exploitability
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Is a vulnerable build present?
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- Affected versionversion=6.18
- Affected versionversion=6471658dc66c670580a7616e75f51b52917e7883 <088ca99dbb039c444c3ff987c5412a73f4f0cbf8
- Affected versionversion=6471658dc66c670580a7616e75f51b52917e7883 <2ef02ac38d3c17f34a00c4b267d961a8d4b45d1a
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What is affected?
Published CVSS scores
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Attacks
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