CVE-2021-26305: 
Rust vulnerability analysis and mitigation

An issue was discovered in Deserializer::read_vec in the cdr crate before 0.2.4 for Rust. The vulnerability (CVE-2021-26305) involves passing an uninitialized buffer to a user-provided Read implementation, which could lead to unauthorized access to old contents of newly allocated heap memory (RUSTSEC Advisory, NVD).

The vulnerability exists in the Deserializer::read_vec() function where it creates an uninitialized buffer and passes it to a user-provided Read implementation through Deserializer.reader.read_exact(). According to Rust's official documentation for the Read trait, passing an uninitialized buffer to an arbitrary Read implementation is defined as undefined behavior. The issue was fixed in version 0.2.4 by implementing zero-initialization of the newly allocated buffer before passing it to Deserializer.reader.read_exact() (RUSTSEC Advisory).

The vulnerability allows unauthorized access to the old contents of newly allocated heap memory, violating memory safety principles. The CVSS v3.1 base score is 9.8 (CRITICAL), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H, indicating high potential impact on confidentiality, integrity, and availability (NVD).

The vulnerability can be exploited through a user-provided Read implementation, requiring no special privileges or user interaction. The attack vector is network-accessible with low attack complexity (RUSTSEC Advisory).

The vulnerability was fixed in cdr version 0.2.4 and later. Users should upgrade to this version or newer to address the issue. The fix involves zero-initializing newly allocated buffers before passing them to the Read implementation (RUSTSEC Advisory).