CVE-2021-29952

Name: CVE-2021-29952
Creator: NVD / NIST
Published: 2021-06-24T14:15:09.973+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

HIGHCVSS 7.5/10EPSS 0.73%

Last modified Jun 17, 2026

CVE-2021-29952 is a high-severity vulnerability rated 7.5/10 on the CVSS scale. When Web Render components were destructed, a race condition could have caused undefined behavior, and we presume that with enough effort may have been exploitable to run arbitrary code. This vulnerability affects Firefox < 88.0.1 and Firefox for Android < 88.1.3.. EPSS estimates a 0.73% chance of exploitation in the next 30 days.

Description

When Web Render components were destructed, a race condition could have caused undefined behavior, and we presume that with enough effort may have been exploitable to run arbitrary code. This vulnerability affects Firefox < 88.0.1 and Firefox for Android < 88.1.3.

Metrics

CVSS 3.1

7.5/10

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

EPSS Probability

0.73%

49.5th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-362

Affected Software

Vendor	Product	Versions
Mozilla	Firefox	< 88.0.1
Mozilla	Firefox	< 88.1.3

References

https://bugzilla.mozilla.org/show_bug.cgi?id=1704227Permissions Required, Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2021-20/Release Notes, Vendor Advisory
https://bugzilla.mozilla.org/show_bug.cgi?id=1704227Permissions Required, Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2021-20/Release Notes, Vendor Advisory

Timeline

Published: Jun 24, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-29952?

How severe is CVE-2021-29952?

CVE-2021-29952 has a CVSS score of 7.5/10 (HIGH severity). The EPSS model estimates a 0.73% probability of exploitation in the next 30 days.

How do I fix CVE-2021-29952?

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-2021-29952?

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

Scan your code now

Source: NVD / NIST