Mozilla Foundation Security Advisory 2026-63

Security Vulnerabilities fixed in Thunderbird 152.0.1

Announced
June 30, 2026
Impact
high
Products
Thunderbird
Fixed in
  • Thunderbird 152.0.1

In general, these flaws cannot be exploited through email in the Thunderbird product because scripting is disabled when reading mail, but are potentially risks in browser or browser-like contexts.

#CVE-2026-57962: Denial-of-service via malicious LDAP address-book server

Reporter
Michael Bommarito
Impact
medium
Description

A malicious LDAP server, which a Thunderbird user is configured to query for address-book autocomplete, can stash arbitrarily large amounts of attacker-supplied data into the Thunderbird LDAP client until it crashes due to memory exhaustion.

References

#CVE-2026-57963: Chat UI manipulation by injection

Reporter
Michael Bommarito
Impact
high
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.

References