CVE-2026-57963

🔶 medium

Summary

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

EPSS Score

0.2

Exploit Probability

Published Date

2026-07-01

First Seen: 2026-07-02

📊 Relative Risk Intelligence

This CVE is Lower Risk - more severe than 47.6% of all 338,292 vulnerabilities in our database.

#177,181

Below average severity

Severity Percentile

🎯 CISA SSVC Assessment Updated: Jul 1, 2026

🔍 Exploitation Status

None

No known exploits

⚙️ Automatable

YES

Can be exploited automatically

💥 Technical Impact

Partial

Limited system impact

🏆 Discovered By

Michael Bommarito

SSVC data provided by CISA

Last Modified 2026-07-06

Source NVD 🔗

CVSS Vector 3.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

CWE IDs (Weakness Types)

CWE-79

📦 Affected Products 2

Vendor	Product	Status	Affected Versions
mozilla	thunderbird	Affected	< 140.12.1
mozilla	thunderbird	Affected	< 152.0.1

🔗 References 3

https://bugzilla.mozilla.org/show_bug.cgi?id=2042910

Permissions Required

https://www.mozilla.org/security/advisories/mfsa2026...

Vendor Advisory

https://www.mozilla.org/security/advisories/mfsa2026...

Vendor Advisory

🔗 Related CVEs 6

CVE ID	Severity	CVSS	EPSS	Summary	Published
CVE-2026-16349	⛔ critical	9.8	0.2	Same-origin policy bypass in the DOM: Navigation component. This vulnerability was fixed in Firefox 153, Firefox ESR 115...	2026-07-21
CVE-2026-16350	⛔ critical	9.8	0.4	Incorrect boundary conditions in the Audio/Video: cubeb component. This vulnerability was fixed in Firefox 153, Firefox ...	2026-07-21
CVE-2026-16351	⛔ critical	9.8	0.4	Sandbox escape due to use-after-free in the DOM: Navigation component. This vulnerability was fixed in Firefox 153, Fire...	2026-07-21
CVE-2026-16352	⛔ critical	9.8	0.4	Sandbox escape due to use-after-free in the Disability Access APIs component. This vulnerability was fixed in Firefox 15...	2026-07-21
CVE-2026-16353	⛔ critical	9.8	0.4	Invalid pointer in the DOM: Bindings (WebIDL) component. This vulnerability was fixed in Firefox 153, Firefox ESR 115.38...	2026-07-21
CVE-2026-16354	⚠️ high	7.5	0.3	Information disclosure in the Graphics: ImageLib component. This vulnerability was fixed in Firefox 153, Firefox ESR 115...	2026-07-21

These CVEs affect the same products