---
id: CVE-2026-113866
title: Account password sent unencrypted during Exchange account setup
summary: >-
  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
  netwo…
severity: medium
cvss: 5.9
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N'
cvssSource: adp
vendor: Mozilla
product: Thunderbird
affected:
  - Thunderbird
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-10-20T19:35:34.601906Z'
published: '2026-10-20'
updated: '2026-10-20'
sourceUpdated: '2026-10-20T19:46:38.284Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-113866'
references:
  - url: 'https://bugzilla.mozilla.org/show_bug.cgi?id=2080121'
  - url: 'https://www.mozilla.org/security/advisories/mfsa2026-114/'
  - url: 'https://www.mozilla.org/security/advisories/mfsa2026-115/'
tags:
  - cve.org
ingestedAt: '2026-10-20T20:18:14.530Z'
---

## Overview

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.

## Affected

- `Thunderbird`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.