CVE-2026-0818

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.

The following products are affected by CVE-2026-0818 vulnerability.

Here, you will find a curated list of external links that provide in-depth information to CVE-2026-0818.

URL	Resource
https://bugzilla.mozilla.org/show_bug.cgi?id=1881530
https://lists.debian.org/debian-lts-announce/2026/02/msg00005.html
https://nvd.nist.gov/vuln/detail/CVE-2026-0818
https://www.cve.org/CVERecord?id=CVE-2026-0818
https://www.mozilla.org/security/advisories/mfsa2026-07/
https://www.mozilla.org/security/advisories/mfsa2026-07/#CVE-2026-0818
https://www.mozilla.org/security/advisories/mfsa2026-08/