Critical RCU Lockup Vulnerability in Linux Kernel - CVE-2025-39744
Summary
CVE-2025-39744: In the Linux kernel, the following vulnerability has been resolved: rcu: Fix rcu_read_unlock() deadloop due to IRQ work During rcu_read_unlock_special(), if this happens during irq_exit(), we can lockup if an IPI is issu... Affects linux versions 5.10.103-1 – 6.9.9-1. No fix is published. How to fix ↓
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Background
The Linux kernel is the core component of many operating systems, responsible for managing hardware resources and providing essential services to software applications. It is widely used in various environments, from servers to embedded systems. This vulnerability affects multiple Debian versions (11, 12, 13, and 14) of the Linux package, highlighting its critical role in system stability and security.
Vulnerability Detail
In the Linux kernel, a vulnerability has been identified that can lead to a deadlock during the execution of the rcu_read_unlock_special() function. This issue arises when an interrupt (IRQ) work is triggered during the IRQ exit process, causing a recursive lockup. The vulnerability was discovered when a BPF program was invoked on the trace_tick_stop() tracepoint, leading to a system hang. The root cause is the improper management of the irq_work state, which can severely impact system performance and reliability.
How To Fix
No fixed version is published for this vulnerability.
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Workaround
As a temporary workaround, users can avoid triggering the IRQ work during the execution of the rcu_read_unlock_special() function. However, this is not a permanent solution and updating the package is strongly recommended.
Conclusion
The CVE-2025-39744 vulnerability in the Linux kernel poses a significant risk to system stability due to potential deadlocks during IRQ processing. Users are urged to update their systems to the patched versions to mitigate this risk. Utilizing tools like Vulert can help monitor for such vulnerabilities effectively.
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FAQ
CVE-2025-39744 is a vulnerability in the Linux kernel that can cause a deadlock due to improper handling of interrupt work during the IRQ exit process.
Debian versions 11, 12, 13, and 14 are affected by this vulnerability.
You can use the Vulert platform to monitor and alert for open-source vulnerabilities in your software. Visit Vulert Scanner to check if your application is affected without requiring any signup.
If exploited, this vulnerability can lead to system hangs and degraded performance, affecting the overall stability of the operating system.
Yes, patches are available for Debian 13 (version 6.12.43-1) and Debian 14 (version 6.16.3-1). It is recommended to update to these versions.
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