CVE-2026-113866

Fixed in a distro release EPSS <1%CVSS 5.9

When setting up an account, Thunderbird's Exchange AutoDiscover lookup also queried the domain's AutoDiscover service over plain HTTP. Due to a bug, that unencrypted request included the credentials the user had entered, allowing a network attacker to obtain the user's password. This vulnerability was fixed in Thunderbird 158.0.1 and Thunderbird 153.5.1.

Published 2026-10-20 · CVE record · OSV

Products: Mozilla Thunderbird

Distro releases