Local service hang via ctnetlink reference leak
Published Sep 4, 2025 · Updated Sep 8, 2026
Denial of service in Linux netfilter ctnetlink allows local users to hang network namespace teardown through repeated table dumps. In ctnetlink_dump_table(), an error path increments an already-held conntrack reference when the current object equals the saved object and never releases the extra reference. Low-privileged local access and repeated dump activity are required; the leaked object keeps the namespace count nonzero, causing cleanup or module removal to wait indefinitely.
Summary
What happened
Denial of service in Linux netfilter ctnetlink allows local users to hang network namespace teardown through repeated table dumps. In ctnetlink_dump_table(), an error path increments an already-held conntrack reference when the current object equals the saved object and never releases the extra reference. Low-privileged local access and repeated dump activity are required; the leaked object keeps the namespace count nonzero, causing cleanup or module removal to wait indefinitely.
The record
- CVE
- CVE-2025-38721
- Published
- Sep 4, 2025
- Updated
- Sep 8, 2026
- Vendor
- Siemens
- Product
- SIPLUS S7-1500 CPU 1518-4 PN/DP MFP
- Classifications
- CWE-20, T1499
- Attack vector
- local
- Privileges
- authenticated
Timeline
How it unfolded
- Sep 4, 2025CVE publishedPublication date reported by the CVE source.
- Sep 8, 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=V3.1.5 <*
- Affected versionversion=V3.1.6 <*
What conditions does exploitation require?
What is affected?
Published CVSS scores
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Attacks
What attackers are doing with it
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Public exploit references
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Technologies
Your stack
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Your stack
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