CVE-2021-38496

Name: CVE-2021-38496
Creator: NVD / NIST
Published: 2021-11-03T01:15:07.38+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

HIGHCVSS 8.8/10EPSS 1.59%

Last modified Jun 17, 2026

CVE-2021-38496 is a high-severity vulnerability rated 8.8/10 on the CVSS scale. During operations on MessageTasks, a task may have been removed while it was still scheduled, resulting in memory corruption and a potentially exploitable crash. This vulnerability affects Thunderbird < 78.15, Thunderbird < 91.2, Firefox ESR < 91.2, Firefox ESR < 78.15, and Firefox < 93.. EPSS estimates a 1.59% chance of exploitation in the next 30 days.

Description

During operations on MessageTasks, a task may have been removed while it was still scheduled, resulting in memory corruption and a potentially exploitable crash. This vulnerability affects Thunderbird < 78.15, Thunderbird < 91.2, Firefox ESR < 91.2, Firefox ESR < 78.15, and Firefox < 93.

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

1.59%

72.6th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-416

Affected Software

Vendor	Product	Versions
Mozilla	Firefox	< 93.0
Mozilla	Firefox	>= 91.0, < 91.2
Mozilla	Firefox Esr	< 78.15
Mozilla	Thunderbird	< 78.15
Mozilla	Thunderbird	>= 91.0, < 91.2
Debian	Debian Linux	9.0
Debian	Debian Linux	10.0
Debian	Debian Linux	11.0

References

https://bugzilla.mozilla.org/show_bug.cgi?id=1725335Issue Tracking, Permissions Required, Vendor Advisory
https://lists.debian.org/debian-lts-announce/2022/01/msg00001.htmlMailing List, Third Party Advisory
https://www.debian.org/security/2022/dsa-5034Issue Tracking, Third Party Advisory
https://www.mozilla.org/security/advisories/mfsa2021-43/Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2021-44/Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2021-45/Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2021-46/Broken Link
https://www.mozilla.org/security/advisories/mfsa2021-47/Vendor Advisory
https://bugzilla.mozilla.org/show_bug.cgi?id=1725335Issue Tracking, Permissions Required, Vendor Advisory
https://lists.debian.org/debian-lts-announce/2022/01/msg00001.htmlMailing List, Third Party Advisory
https://www.debian.org/security/2022/dsa-5034Issue Tracking, Third Party Advisory
https://www.mozilla.org/security/advisories/mfsa2021-43/Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2021-44/Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2021-45/Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2021-46/Broken Link
https://www.mozilla.org/security/advisories/mfsa2021-47/Vendor Advisory

Timeline

Published: Nov 3, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-38496?

How severe is CVE-2021-38496?

CVE-2021-38496 has a CVSS score of 8.8/10 (HIGH severity). The EPSS model estimates a 1.59% probability of exploitation in the next 30 days.

How do I fix CVE-2021-38496?

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-2021-38496?

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

Scan your code now

Source: NVD / NIST