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MEDIUM · 6.5

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. This vulnerability was fixed in Thunderbird ...

Vulnerability Description

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.

CVSS Score

6.5

MEDIUM

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
LOW
Integrity
LOW
Availability
NONE

Affected Products

VendorProductVersions
MozillaThunderbird< 140.12.1

Related Weaknesses (CWE)

CWE-79

References

FAQ

What is CVE-2026-57963?

CVE-2026-57963 is a vulnerability with a CVSS score of 6.5 (MEDIUM). 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 ...

How severe is CVE-2026-57963?

CVE-2026-57963 has been rated MEDIUM with a CVSS base score of 6.5/10. Review the CVSS metrics above for detailed severity breakdown.

Is there a patch for CVE-2026-57963?

Check the references section above for vendor advisories and patch information. Affected products include: Mozilla Thunderbird.