Local kernel crash via stale namespace pointer
Published Jan 19, 2025 · Updated May 12, 2026
NULL pointer dereference in Linux SCTP sysctl handling allows local users to crash affected systems while a task exits. The rto_min and rto_max handlers in net/sctp/sysctl.c obtain the network namespace through current->nsproxy, which can be NULL during task teardown, instead of deriving the opener's namespace from table->data. Reachability requires local low-privileged access and task exit while either handler runs; the reported consequence is a kernel Oops and service interruption.
Summary
What happened
NULL pointer dereference in Linux SCTP sysctl handling allows local users to crash affected systems while a task exits. The rto_min and rto_max handlers in net/sctp/sysctl.c obtain the network namespace through current->nsproxy, which can be NULL during task teardown, instead of deriving the opener's namespace from table->data. Reachability requires local low-privileged access and task exit while either handler runs; the reported consequence is a kernel Oops and service interruption.
The record
- CVE
- CVE-2025-21639
- Published
- Jan 19, 2025
- Updated
- May 12, 2026
- Vendor
- Siemens
- Product
- SIMATIC S7-1500 TM MFP - GNU/Linux subsystem
- Classifications
- CWE-476, T1499.004
- Attack vector
- local
- Privileges
- authenticated
Timeline
How it unfolded
- Jan 19, 2025CVE publishedPublication date reported by the CVE source.
- May 12, 2026Record updatedLatest update available in the CVE record.
Exploitability
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- Affected versionversion=0 <*
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Published CVSS scores
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