CVE-2026-113866

EUVD-2026-105293
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.
ProviderTypeBase ScoreAtk. VectorAtk. ComplexityPriv. RequiredVector
mozillaCNA
5.9 MEDIUM
NETWORK
HIGH
NONE
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
Base Score
CVSS 3.x
EPSS Score
Percentile: 29.08%
Early Detection
Affected products identified ahead of NVD analysis through intelligence sources.
VendorProductVersionSource
mozillathunderbird_esr
𝑥
< 153.5.1
CNA
Common Weakness Enumeration
Vulnerability Media Exposure
References
https://bugzilla.mozilla.org/show_bug.cgi?id=2080121
https://www.mozilla.org/security/advisories/mfsa2026-114/
https://www.mozilla.org/security/advisories/mfsa2026-115/