CVE-2021-26958: Xcb Project Xcb

High severity, CVSS 8.8. EPSS: 1.6% chance of exploitation in the next 30 days.

An issue was discovered in the xcb crate through 2021-02-04 for Rust. It has a soundness violation because transmutation to the wrong type can happen after xcb::base::cast_event uses std::mem::transmute to return a reference to an arbitrary type.

Affected products

• Xcb Project Xcb: up to and including 2021-02-04

Published 2021-02-09. Last modified 2026-06-17.