CVE-2021-29939: 
Rust vulnerability analysis and mitigation

An issue was discovered in the stackvector crate through 2021-02-19 for Rust. The vulnerability (CVE-2021-29939) involves an out-of-bounds write in StackVec::extend functionality when size_hint provides certain anomalous data (RustSec Advisory, NVD).

The vulnerability occurs in the StackVec::extend implementation which uses the lower and upper bounds from an Iterator's sizehint to determine how many items to push into the stack-based vector. If the sizehint implementation returns a lower bound larger than the upper bound, StackVec would write out of bounds and overwrite memory on the stack. The issue has a CVSS v3.1 base score of 7.3 (High) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L (RustSec Advisory).

When exploited, this vulnerability can lead to memory corruption through out-of-bounds write operations on the stack. This could potentially result in system crashes or arbitrary code execution, affecting the confidentiality, integrity, and availability of the system (RustSec Advisory).

The vulnerability has been patched in version 1.0.9 of the stackvector crate. Users are advised to upgrade to this version or later to address the security issue (RustSec Advisory).