CVE-2026-14899 Affecting thunderbird package, versions <0:140.13.0-1.el9_8.alma.1


Severity

Recommended
high

Based on AlmaLinux security rating.

Threat Intelligence

EPSS
0.27% (20th percentile)

Do your applications use this vulnerable package?

In a few clicks we can analyze your entire application and see what components are vulnerable in your application, and suggest you quick fixes.

Test your applications
  • Snyk IDSNYK-ALMALINUX9-THUNDERBIRD-18578499
  • published7 Aug 2026
  • disclosed3 Aug 2026

Introduced: 3 Aug 2026

NewCVE-2026-14899  (opens in a new tab)

How to fix?

Upgrade AlmaLinux:9 thunderbird to version 0:140.13.0-1.el9_8.alma.1 or higher.
This issue was patched in ALSA-2026:49921.

NVD Description

Note: Versions mentioned in the description apply only to the upstream thunderbird package and not the thunderbird package as distributed by AlmaLinux. See How to fix? for AlmaLinux:9 relevant fixed versions and status.

The code to parse MIME headers for display when forwarding a message (if the setting to view all headers was enabled) had an off-by-one error, allowing a single byte to be read from the memory after the buffer for the headers, and potentially crashing Thunderbird. This vulnerability was fixed in Thunderbird 153 and Thunderbird 140.13.

CVSS Base Scores

version 3.1