CVE-2026-74428 in Linux
Summary
by MITRE • 08/15/2026
In the Linux kernel, the following vulnerability has been resolved:
rxrpc: Fix double unlock in rxrpc_recvmsg()
Fix a double unlock in rxrpc_recvmsg() when dealing with OOB messages.
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Analysis
by VulDB Data Team • 08/15/2026
The vulnerability resides within the Linux kernel's remote execution interface implementation, specifically in the rxrpc subsystem responsible for handling remote procedure calls over unreliable datagram protocols. This issue manifests as a double unlock condition occurring during message processing when out-of-band data is encountered. The rxrpc_recvmsg() function processes incoming messages and manages kernel locks to ensure thread safety during concurrent access to shared resources. When an out-of-band message triggers the code path, the locking mechanism fails to properly handle the release of acquired locks, resulting in a scenario where the same lock is unlocked twice.
The technical flaw stems from improper lock management within the rxrpc subsystem's receive message handling routine. During normal operation, the function acquires a lock to protect critical sections of code while processing incoming data. However, when out-of-band messages are processed, control flow diverges in a manner that leads to duplicate unlock operations. This condition violates fundamental locking principles and can result in undefined behavior including potential kernel crashes or memory corruption. The vulnerability represents a classic example of improper resource management where lock acquisition and release patterns are not properly maintained across different execution paths.
The operational impact of this vulnerability extends beyond simple system stability concerns as it could potentially be exploited by malicious actors to cause denial of service conditions or even escalate privileges within the kernel space. When the double unlock occurs, the kernel's memory management structures may become corrupted, leading to unpredictable behavior that could manifest as system panics, data loss, or compromised security boundaries. The vulnerability is particularly concerning because it operates at the kernel level where errors can have cascading effects on all system operations and potentially provide attackers with opportunities to bypass security mechanisms.
The fix implemented addresses the root cause by ensuring proper lock management throughout all code paths within rxrpc_recvmsg(). This typically involves restructuring conditional logic to prevent duplicate unlock calls or employing more robust locking primitives that can handle multiple unlock attempts gracefully. The solution aligns with common security practices for kernel development and follows established patterns for resource management in concurrent environments. From a cybersecurity perspective, this vulnerability falls under the category of improper locking mechanisms that can be classified as CWE-121, which relates to buffer overflow conditions. The fix demonstrates adherence to secure coding principles and proper resource management techniques that help maintain system integrity.
Mitigation strategies for this vulnerability include applying the relevant kernel security patches immediately upon release, monitoring system logs for potential signs of kernel instability, and implementing comprehensive endpoint protection measures that can detect anomalous behavior patterns. System administrators should prioritize patch deployment across all affected systems and consider conducting thorough testing to ensure compatibility with existing network configurations. Additional defensive measures may include implementing network segmentation to limit exposure to potentially malicious traffic and establishing robust monitoring protocols for detecting system crashes or unusual resource consumption patterns that could indicate exploitation attempts. The vulnerability serves as a reminder of the critical importance of maintaining up-to-date kernel security patches and proper code review processes in preventing exploitation of low-level system vulnerabilities that could compromise entire network infrastructures.