CVE-2026-57963: An attacker who can send HTML chat messages (via Matrix or XMPP) can inject arbitrary styled content, phishing links, and CSS that manipulates the chat UI…

PriorityP336medium6.5CVSS 3.1

AVNACLPRNUINSUCLILAN

EPSS

0.18%

7.8th percentile

An attacker who can send HTML chat messages (via Matrix or XMPP) can inject arbitrary styled content, phishing links, and CSS that manipulates the chat UI. This vulnerability was fixed in Thunderbird 152.0.1 and Thunderbird 140.12.1.

Affected

4 ranges

Vendor	Product	Version range	Fixed in
mozilla	thunderbird	< Thunderbird 152.0.1	Thunderbird 152.0.1
mozilla	thunderbird	< Thunderbird 140.12.1	Thunderbird 140.12.1
mozilla	thunderbird	< 140.12.1	140.12.1
mozilla	thunderbird	< 152.0.1	152.0.1

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