CVE-2026-92239 Buffer overrun in IMAP
A malicious IMAP line triggers an out-of-bounds buffer read in Thunderbird, potentially causing crashes or code execution.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-92239?
CVE-2026-92239 is a high-severity memory corruption vulnerability in Mozilla Thunderbird, published on 15 Sep 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official description
A maliciously constructed IMAP line could cause an out-of-bounds buffer read. This vulnerability was fixed in Thunderbird 156, Thunderbird 140.16, and Thunderbird 153.3.
Weakness: CWE-125
Which versions are affected by CVE-2026-92239?
It affects 1 product.
Products include Mozilla Thunderbird.
How do I fix CVE-2026-92239?
Upgrade to a fixed version.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-92239 being exploited?
There is no known exploitation of CVE-2026-92239 in the wild and no public exploit code.
Other vulnerabilities in Mozilla Thunderbird
Sources
Also known as DEBIAN-CVE-2026-92239, GHSA-3f4g-x8c6-4887, UBUNTU-CVE-2026-92239.