CVE-2026-113866
MEDIUM
CVSS 5.9
Published: 2026-10-20
Modified: 2026-10-20
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Description
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.
Quick Facts
| CVE ID | CVE-2026-113866 |
| CVSS Score | 5.9 |
| Vector | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N |
| Published | 2026-10-20 |
| Exploited | No |
| CISA KEV | No |
| PoC | Not public |