CVE-2020-36220 in va-ts Crate
Summary
by MITRE • 01/26/2021
An issue was discovered in the va-ts crate before 0.0.4 for Rust. Because Demuxer omits a required T: Send bound, a data race and memory corruption can occur.
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Analysis
by VulDB Data Team • 02/20/2021
The vulnerability identified as CVE-2020-36220 resides within the va-ts crate version 0.0.3 and earlier, representing a critical concurrency flaw that undermines memory safety guarantees in Rust applications. This issue manifests through improper type constraint handling within the Demuxer implementation, specifically failing to enforce the essential T: Send bound requirement. The absence of this bound creates a dangerous pathway for concurrent execution where data structures may be accessed simultaneously from multiple threads without proper synchronization mechanisms. The vulnerability directly impacts the crate's ability to safely handle multithreaded scenarios involving time-stamped data streams, which are common in multimedia processing and real-time systems.
The technical root cause stems from Rust's ownership model being bypassed through the omission of the Send trait bound, which is fundamental for ensuring types can be safely transferred between threads. When a type does not implement Send, it indicates that the type contains non-thread-safe elements or references that could become invalid when moved across thread boundaries. The Demuxer structure, which processes time-stamped data streams, relies on shared mutable state that becomes vulnerable when the T parameter lacks the Send constraint. This flaw allows for race conditions where multiple threads might simultaneously access and modify the same memory locations, leading to unpredictable behavior and potential memory corruption. The vulnerability aligns with CWE-362, which specifically addresses Race Conditions, and demonstrates how improper trait bounds can create security-relevant concurrency issues in memory-safe languages.
The operational impact of this vulnerability extends beyond simple performance degradation to encompass potential system instability and security risks. Applications utilizing the affected crate may experience crashes, data corruption, or even arbitrary code execution if attackers can manipulate the timing of concurrent operations to trigger memory safety violations. The vulnerability is particularly concerning in multimedia applications, streaming services, or any system processing time-stamped data where multiple threads might be involved in demuxing operations. Memory corruption resulting from this race condition could lead to exploitable conditions where an attacker might manipulate the corrupted memory to execute malicious code, especially when combined with other vulnerabilities in the application stack. This represents a classic example of how seemingly minor type constraint issues can create significant security implications in concurrent systems.
Mitigation strategies for CVE-2020-36220 focus on upgrading to version 0.0.4 or later of the va-ts crate where the required T: Send bound has been properly implemented. System administrators and developers should conduct thorough dependency audits to identify all applications and services using affected versions of the crate, particularly in environments handling multimedia data streams or real-time processing. Additionally, implementing proper thread synchronization mechanisms and memory safety checks within applications can provide defense-in-depth measures. The fix addresses the underlying concurrency issue by ensuring that all types used with the Demuxer properly implement the Send trait, thereby preventing unsafe cross-thread data sharing. Organizations should also consider implementing continuous monitoring for similar issues in their dependency chains, as this vulnerability demonstrates how subtle type system violations can create security-relevant flaws. This issue highlights the importance of rigorous code review processes and automated security testing that specifically targets memory safety and concurrency-related issues in Rust applications, aligning with ATT&CK technique T1068 which covers exploit for privilege escalation through memory corruption vulnerabilities.