CVE-2017-20004 in Standard Library
Summary
by MITRE • 04/14/2021
In the standard library in Rust before 1.19.0, there is a synchronization problem in the MutexGuard object. MutexGuards can be used across threads with any types, allowing for memory safety issues through race conditions.
If you want to get the best quality for vulnerability data then you always have to consider VulDB.
Analysis
by VulDB Data Team • 04/17/2021
The vulnerability identified as CVE-2017-20004 resides within the Rust standard library's concurrency primitives, specifically affecting versions prior to 1.19.0. This issue manifests in the MutexGuard object implementation where the synchronization mechanisms fail to properly enforce thread safety guarantees. The fundamental problem lies in how MutexGuard objects handle cross-thread usage, creating a scenario where developers can inadvertently pass or share MutexGuard instances between different threads without proper synchronization enforcement.
The technical flaw stems from inadequate thread-local storage management and missing runtime checks within the MutexGuard implementation. When a MutexGuard is created, it should strictly bind to the thread that acquired the lock, preventing any possibility of cross-thread access patterns that could lead to data races. However, in affected versions, the implementation allowed for scenarios where the guard could be moved or shared across thread boundaries, effectively bypassing the memory safety guarantees that Rust's ownership system is designed to provide. This represents a violation of the fundamental concurrency safety principles that Rust promotes, particularly concerning the elimination of data races through compile-time enforcement.
The operational impact of this vulnerability extends beyond simple memory corruption, as it creates potential attack vectors for malicious actors seeking to exploit race conditions in concurrent applications. When developers incorrectly assume that MutexGuard objects provide automatic thread safety guarantees, they may write code that appears correct but actually introduces subtle concurrency bugs. These race conditions can manifest as unpredictable behavior, data corruption, or even security vulnerabilities if the affected applications handle sensitive data. The vulnerability is particularly concerning in systems where Rust is used for security-critical applications, as it undermines the language's core safety promises and can lead to exploitation of memory safety issues that would normally be prevented by the type system.
The flaw aligns with CWE-362, which describes a race condition vulnerability in concurrent programming where multiple threads access shared resources without proper synchronization. This vulnerability also maps to ATT&CK technique T1059.007, which involves the use of system services or libraries to execute malicious code, as the improper mutex handling could potentially be leveraged to create exploitable conditions in concurrent environments. Additionally, the issue relates to CWE-129, concerning improper validation of array indices, as the race condition can lead to memory access violations that occur when the guard's internal state becomes inconsistent across threads.
Mitigation strategies for CVE-2017-20004 require immediate upgrading to Rust version 1.19.0 or later, where the MutexGuard implementation was corrected to properly enforce thread-local binding and prevent cross-thread usage patterns. Developers should conduct thorough code reviews to identify any instances where MutexGuard objects might be inadvertently shared across threads, particularly in complex concurrent applications. The fix implemented in version 1.19.0 enforces stricter compile-time checking and runtime validation to ensure that MutexGuard objects cannot be moved between threads, thereby maintaining the memory safety guarantees that Rust's concurrency model is designed to provide. Organizations should also implement automated testing procedures that specifically validate concurrent access patterns to prevent similar issues from emerging in future code deployments.