CVE-2026-0818 Affecting thunderbird package, versions <1:140.7.1esr-1~deb12u1


Severity

Recommended
low

Based on default assessment until relevant scores are available.

Threat Intelligence

EPSS
0.16% (6th percentile)

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  • Snyk IDSNYK-ECHOLATEST-THUNDERBIRD-18318884
  • published26 Jul 2026
  • disclosed28 Jan 2026

Introduced: 28 Jan 2026

CVE-2026-0818  (opens in a new tab)

How to fix?

Upgrade Echo:latest thunderbird to version 1:140.7.1esr-1~deb12u1 or higher.

NVD Description

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

When a user explicitly requested Thunderbird to decrypt an inline OpenPGP message that was embedded in a text section of an email that was formatted and styled with HTML and CSS, then the decrypted contents were rendered in a context in which the CSS styles from the outer messages were active. If the user had additionally allowed loading of the remote content referenced by the outer email message, and the email was crafted by the sender using a combination of CSS rules and fonts and animations, then it was possible to extract the secret contents of the email. This vulnerability was fixed in Thunderbird 147.0.1 and Thunderbird 140.7.1.

CVSS Base Scores

version 3.1