Local system crash via uninitialized drop_monitor spinlock
Published Mar 12, 2025 · Updated Jul 14, 2026
Use of an uninitialized spinlock in the Linux kernel allows local users to crash the system through a Netlink race. When drop_monitor is built as a module, its initialization registers the Generic Netlink family before initializing the per-CPU spinlock used by net_dm_monitor_start(). A local low-privilege user who wins the module-loading race with NET_DM_CMD_START reaches the invalid lock and can interrupt service by crashing the kernel.
Summary
What happened
Use of an uninitialized spinlock in the Linux kernel allows local users to crash the system through a Netlink race. When drop_monitor is built as a module, its initialization registers the Generic Netlink family before initializing the per-CPU spinlock used by net_dm_monitor_start(). A local low-privilege user who wins the module-loading race with NET_DM_CMD_START reaches the invalid lock and can interrupt service by crashing the kernel.
The record
- CVE
- CVE-2025-21862
- Published
- Mar 12, 2025
- Updated
- Jul 14, 2026
- Vendor
- Siemens
- Product
- SIPLUS S7-1500 CPU 1518-4 PN/DP MFP
- Classifications
- CWE-908, T1499
- Attack vector
- local
- Privileges
- authenticated
Timeline
How it unfolded
- Mar 12, 2025CVE publishedPublication date reported by the CVE source.
- Jul 14, 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 <*
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What is affected?
Published CVSS scores
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Attacks
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Public exploit references
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Technologies
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Your stack
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