CVE-2021-29970

Name: CVE-2021-29970
Creator: NVD / NIST
Published: 2021-08-05T20:15:08.54+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

HIGHCVSS 8.8/10EPSS 1.43%

Last modified Jun 17, 2026

CVE-2021-29970 is a high-severity vulnerability rated 8.8/10 on the CVSS scale. A malicious webpage could have triggered a use-after-free, memory corruption, and a potentially exploitable crash. *This bug could only be triggered when accessibility was enabled.*. EPSS estimates a 1.43% chance of exploitation in the next 30 days.

Description

A malicious webpage could have triggered a use-after-free, memory corruption, and a potentially exploitable crash. *This bug could only be triggered when accessibility was enabled.*. This vulnerability affects Thunderbird < 78.12, Firefox ESR < 78.12, and Firefox < 90.

Metrics

CVSS 3.1

8.8/10

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

EPSS Probability

1.43%

69.6th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Mozilla	Firefox	< 90.0
Mozilla	Firefox Esr	< 78.12
Mozilla	Thunderbird	< 78.12

References

https://bugzilla.mozilla.org/show_bug.cgi?id=1709976Exploit, Issue Tracking, Vendor Advisory
https://security.gentoo.org/glsa/202202-03Third Party Advisory
https://security.gentoo.org/glsa/202208-14Third Party Advisory
https://www.mozilla.org/security/advisories/mfsa2021-28/Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2021-29/Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2021-30/Vendor Advisory
https://bugzilla.mozilla.org/show_bug.cgi?id=1709976Exploit, Issue Tracking, Vendor Advisory
https://security.gentoo.org/glsa/202202-03Third Party Advisory
https://security.gentoo.org/glsa/202208-14Third Party Advisory
https://www.mozilla.org/security/advisories/mfsa2021-28/Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2021-29/Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2021-30/Vendor Advisory

Timeline

Published: Aug 5, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-29970?

How severe is CVE-2021-29970?

CVE-2021-29970 has a CVSS score of 8.8/10 (HIGH severity). The EPSS model estimates a 1.43% probability of exploitation in the next 30 days.

How do I fix CVE-2021-29970?

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-2021-29970?

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

Scan your code now

Source: NVD / NIST