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 f

mediumCVSS 6.5CVE-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 152.0.1 and Thunderbird 140.12.1.

Details

Source: NVD Recent CVEs (US · database · site)
Severity: medium — CVSS 6.5
Published: 2026-07-01
Last updated: 2026-07-06
Exploitation: Not in CISA KEV at last sync

Original advisory: https://nvd.nist.gov/vuln/detail/CVE-2026-57963

Exploitation outlook

EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.

Low exploitation riskCVE-2026-579630.18% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 8% of all scored CVEs.

Referenced CVEs

CVE	CSIRTS overview	External
CVE-2026-57963	coverage & exploitation status	NVD · CVE.org

Same CVEs, other sources

How other CERTs, PSIRTs and databases cover the vulnerabilities in this advisory.

medium[UPDATE] [medium] Mozilla Thunderbird: Multiple vulnerabilitiescert-bund
unknownMozilla Products Multiple Vulnerabilitieshkcert
unknownMultiple vulnerabilities in Mozilla Thunderbird (July 2, 2026)cert-fr-avis

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