CVE-2021-29945

Name: CVE-2021-29945
Creator: NVD / NIST
Published: 2021-06-24T14:15:09.763+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 6.5/10EPSS 1.21%

Last modified Jun 17, 2026

CVE-2021-29945 is a medium-severity vulnerability rated 6.5/10 on the CVSS scale. The WebAssembly JIT could miscalculate the size of a return type, which could lead to a null read and result in a crash. *Note: This issue only affected x86-32 platforms. EPSS estimates a 1.21% chance of exploitation in the next 30 days.

Description

The WebAssembly JIT could miscalculate the size of a return type, which could lead to a null read and result in a crash. *Note: This issue only affected x86-32 platforms. Other platforms are unaffected.*. This vulnerability affects Firefox ESR < 78.10, Thunderbird < 78.10, and Firefox < 88.

Metrics

CVSS 3.1

6.5/10

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

EPSS Probability

1.21%

64.5th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-682

Affected Software

Vendor	Product	Versions
Mozilla	Firefox	< 88.0
Mozilla	Firefox Esr	< 78.10
Mozilla	Thunderbird	< 78.10

References

https://bugzilla.mozilla.org/show_bug.cgi?id=1700690Issue Tracking, Permissions Required, Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2021-14/Release Notes, Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2021-15/Release Notes, Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2021-16/Release Notes, Vendor Advisory
https://bugzilla.mozilla.org/show_bug.cgi?id=1700690Issue Tracking, Permissions Required, Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2021-14/Release Notes, Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2021-15/Release Notes, Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2021-16/Release Notes, Vendor Advisory

Timeline

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

Frequently Asked Questions

What is CVE-2021-29945?

How severe is CVE-2021-29945?

CVE-2021-29945 has a CVSS score of 6.5/10 (MEDIUM severity). The EPSS model estimates a 1.21% probability of exploitation in the next 30 days.

How do I fix CVE-2021-29945?

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-2021-29945?

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

Scan your code now

Source: NVD / NIST