CVE-2014-9748 in libuv
Summary
by MITRE
The uv_rwlock_t fallback implementation for Windows XP and Server 2003 in libuv before 1.7.4 does not properly prevent threads from releasing the locks of other threads, which allows attackers to cause a denial of service (deadlock) or possibly have unspecified other impact by leveraging a race condition.
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Analysis
by VulDB Data Team • 04/22/2023
The vulnerability identified as CVE-2014-9748 affects the libuv library version 1.7.3 and earlier, specifically targeting the uv_rwlock_t fallback implementation designed for Windows XP and Server 2003 operating systems. This flaw represents a critical concurrency issue that undermines the fundamental thread synchronization mechanisms within the library. The root cause lies in the improper implementation of reader-writer lock semantics where the fallback mechanism fails to enforce proper lock ownership validation. When multiple threads attempt to acquire and release locks in a concurrent environment, the flawed implementation allows threads to inadvertently release locks that belong to other threads, creating a dangerous race condition scenario.
The technical implementation defect stems from the library's attempt to provide backward compatibility for older Windows operating systems that lack native support for certain synchronization primitives. The uv_rwlock_t implementation in libuv relies on a custom fallback mechanism that uses Windows critical sections and event objects to simulate reader-writer lock behavior. However, this custom implementation contains a critical flaw in its lock release logic where it does not properly track which thread owns a particular lock resource. This design flaw creates a scenario where a thread can successfully release a lock that was acquired by a different thread, leading to unpredictable behavior and potential system instability.
The operational impact of this vulnerability extends beyond simple denial of service conditions to encompass potential security implications and system instability. An attacker can exploit this race condition to induce deadlocks within applications that depend on libuv for asynchronous I/O operations, effectively causing service disruption. The unspecified other impacts mentioned in the vulnerability description suggest that the flaw could potentially allow for more severe consequences including memory corruption or arbitrary code execution depending on the specific application context and usage patterns. This vulnerability particularly affects applications built on top of node.js and other frameworks that utilize libuv for their underlying I/O handling capabilities, making it a widespread concern across the software ecosystem that relies on asynchronous programming models.
The vulnerability maps directly to CWE-362, which describes a race condition in the context of concurrent execution, and aligns with ATT&CK technique T1499.004 for network denial of service attacks. The flaw demonstrates how improper synchronization primitives can create exploitable conditions that allow attackers to manipulate system resources and potentially compromise application availability. Organizations using affected versions of libuv should implement immediate mitigations including updating to version 1.7.4 or later, which contains the necessary fixes to properly enforce lock ownership semantics. Additionally, system administrators should consider implementing runtime monitoring to detect potential deadlock conditions and application-level defensive programming practices that minimize the impact of such race conditions. The fix implemented in version 1.7.4 involves correcting the lock release mechanism to properly validate thread ownership before allowing lock releases, thereby preventing threads from interfering with each other's synchronization resources and maintaining proper concurrency control within the library's asynchronous I/O framework.