CVE-2020-36216 in eventio Crate
Summary
by MITRE • 01/26/2021
An issue was discovered in Input in the eventio crate before 0.5.1 for Rust. Because a non-Send type can be sent to a different thread, 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-2020-36216 resides within the eventio crate version 0.5.0 and earlier in the Rust programming ecosystem, representing a critical concurrency flaw that undermines memory safety guarantees inherent to the language. This issue specifically affects the handling of non-Send types across thread boundaries, creating a fundamental breach in Rust's ownership and borrowing system that is designed to prevent data races at compile time. The eventio crate serves as an event handling library that facilitates asynchronous operations, making this vulnerability particularly dangerous in applications that rely on concurrent processing and event-driven architectures.
The technical flaw manifests when the crate permits the transmission of types that do not implement the Send trait to different threads, violating Rust's fundamental safety guarantees. The Send trait in Rust indicates that a type can be safely transferred between threads, but when non-Send types are inadvertently moved across thread boundaries, it creates a scenario where multiple threads can simultaneously access the same memory location without proper synchronization. This design flaw directly maps to CWE-362, which describes a concurrency flaw involving the unsafe sharing of resources between threads, and specifically aligns with CWE-1177, which addresses the improper handling of non-Send types in concurrent contexts. The vulnerability creates a pathway for memory corruption through data races that occur when different threads attempt to read and write to the same memory location simultaneously.
The operational impact of this vulnerability extends beyond simple memory corruption, as it can lead to arbitrary code execution and system instability in applications utilizing the affected crate. When non-Send types are moved between threads, the memory layout and access patterns become unpredictable, potentially causing heap corruption, stack overflow conditions, or other memory-related crashes that could be exploited by malicious actors. Applications that depend on eventio for handling asynchronous events, network I/O operations, or user interface interactions become particularly vulnerable, as these scenarios often involve concurrent thread operations. The vulnerability is especially concerning in server-side applications, embedded systems, and any environment where memory safety is paramount, as it undermines the core security assumptions that Rust developers rely upon when building concurrent applications.
Mitigation strategies for CVE-2020-36216 require immediate action to upgrade to eventio version 0.5.1 or later, which implements proper Send trait validation and prevents the unsafe movement of non-Send types across thread boundaries. Organizations should conduct comprehensive code audits to identify any other crates or libraries that might be using similar patterns or have similar vulnerabilities in their dependency trees. The fix implemented in version 0.5.1 likely involves stricter compile-time checks that ensure only Send types can be transmitted between threads, effectively preventing the conditions that led to the data race. Additionally, developers should adopt defensive programming practices such as using thread-safe alternatives like channels or mutexes when sharing data between threads, and implementing proper synchronization mechanisms that align with the Rust concurrency model. This vulnerability serves as a reminder of the importance of rigorous testing and validation in concurrent programming environments, particularly when dealing with low-level memory operations and inter-thread communication patterns that can compromise the fundamental safety guarantees of memory-safe languages like Rust.