CVE-2019-15554 in smallvec Crate
Summary
by MITRE
An issue was discovered in the smallvec crate before 0.6.10 for Rust. There is memory corruption for certain grow attempts with less than the current capacity.
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Analysis
by VulDB Data Team • 12/04/2023
The vulnerability identified as CVE-2019-15554 affects the smallvec crate version 0.6.9 and earlier in the Rust programming language ecosystem. This issue represents a memory corruption flaw that specifically manifests during certain grow operations when the requested capacity is less than the currently allocated capacity. The smallvec crate is widely utilized for efficient memory management in Rust applications, providing a vector-like data structure that can store a small number of elements inline without heap allocation while falling back to heap allocation for larger collections. The flaw occurs in the internal memory management logic of the crate's grow function, which handles capacity expansion when elements are added beyond the current allocated space. When the grow operation attempts to allocate memory with a size that is smaller than the existing capacity, the memory corruption vulnerability is triggered, potentially leading to undefined behavior and system instability.
The technical implementation of this vulnerability stems from improper handling of capacity calculations and memory allocation logic within the smallvec crate's internal algorithms. The flaw specifically manifests when the grow function receives a new capacity parameter that is smaller than the current capacity but larger than the number of elements currently stored. This situation creates a scenario where the memory management code fails to properly handle the existing memory layout, leading to memory corruption that can result in heap corruption, data overwrites, or memory access violations. The underlying issue relates to how the crate manages its internal buffer state and handles capacity adjustments, particularly when transitioning between inline storage and heap allocation. This vulnerability operates at the intersection of memory safety and resource management, representing a classic example of improper memory boundary handling that can be exploited to compromise system integrity.
The operational impact of this vulnerability extends across numerous Rust applications and systems that utilize the smallvec crate for efficient data structure management. Attackers could potentially exploit this memory corruption flaw to execute arbitrary code, cause application crashes, or manipulate memory contents in ways that compromise system security. The vulnerability is particularly concerning because smallvec is a widely used dependency in the Rust ecosystem, meaning that a compromise in this crate could affect multiple downstream applications and services. The memory corruption could be leveraged to bypass security controls, manipulate data structures, or create denial-of-service conditions that disrupt system operations. Given the nature of memory corruption vulnerabilities, the impact can be severe and may not be immediately apparent, potentially allowing for persistent compromise of affected systems. The vulnerability also highlights the importance of proper memory management in systems programming languages where such issues can directly translate to security risks.
Mitigation strategies for CVE-2019-15554 involve immediate upgrading of the smallvec crate to version 0.6.10 or later, which contains the necessary fixes to address the memory corruption issue. System administrators and developers should conduct comprehensive dependency audits to identify all applications and services using vulnerable versions of the crate and ensure proper patching. Additionally, implementing proper input validation and boundary checks in applications that utilize smallvec can help reduce the attack surface. The fix implemented in version 0.6.10 specifically addresses the capacity calculation logic and ensures proper memory allocation handling during grow operations, preventing the conditions that lead to memory corruption. Organizations should also consider implementing runtime memory protection mechanisms such as address space layout randomization and stack canaries to provide additional defense in depth. Regular security scanning and dependency monitoring should be maintained to identify similar vulnerabilities in other third-party libraries that may pose similar risks to system security and integrity. This vulnerability serves as a reminder of the critical importance of proper memory management in systems programming and the need for comprehensive security testing of core library components that form the foundation of many applications.