CVE-2026-113866: Vulnerability in Mozilla Thunderbird
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.
CVSS v3.1
Score 5.9medium
Affected software
Mozilla
Thunderbird
pkg:github/mozilla/thunderbirdRun on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-113866 describes a vulnerability in Mozilla Thunderbird where, during the Exchange AutoDiscover process for account setup, the client queried the domain's AutoDiscover service over plain HTTP. Due to a bug, this unencrypted request included the user's credentials, allowing a network attacker to capture the password. The vulnerability was fixed in Thunderbird 158.0.1.
Potential Impact
An attacker with network access could intercept the unencrypted HTTP request containing user credentials, leading to credential disclosure and potential account compromise.
Mitigation Recommendations
Users should update Thunderbird to version 158.0.1 or later, where this vulnerability has been fixed. No other mitigation is necessary as the issue is resolved by the official patch.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- mozilla
- Date Reserved
- 2026-10-20T19:14:54.467Z
- State
- PUBLISHED
- Vendor Advisory Urls
- [{"url":"https://www.mozilla.org/security/advisories/mfsa2026-114/","vendor":"Mozilla"}]
Threat ID: 6ad7c23c2cdf04f656561a7d
Added to database: 10/20/2026, 19:34:20 UTC
Last enriched: 10/20/2026, 19:48:24 UTC
Last updated: 10/20/2026, 22:32:59 UTC
Views: 9
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