CVE-2021-26958

Name: CVE-2021-26958
Creator: NVD / NIST
Published: 2021-02-09T23:15:14.383+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

HIGHCVSS 8.8/10EPSS 1.60%

Last modified Jun 17, 2026

CVE-2021-26958 is a high-severity vulnerability rated 8.8/10 on the CVSS scale. 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.. EPSS estimates a 1.60% chance of exploitation in the next 30 days.

Description

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.

Metrics

CVSS 3.1

8.8/10

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS Probability

1.60%

72.7th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-252

Affected Software

Vendor	Product	Versions
Xcb Project	Xcb	<= 2021-02-04

References

https://rustsec.org/advisories/RUSTSEC-2021-0019.htmlExploit, Vendor Advisory
https://rustsec.org/advisories/RUSTSEC-2021-0019.htmlExploit, Vendor Advisory

Timeline

Published: Feb 9, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-26958?

How severe is CVE-2021-26958?

CVE-2021-26958 has a CVSS score of 8.8/10 (HIGH severity). The EPSS model estimates a 1.60% probability of exploitation in the next 30 days.

How do I fix CVE-2021-26958?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-26958?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST