CVE-2026-113866
Description
A flaw was found in Thunderbird. An information disclosure issue occurs during account setup when the Exchange AutoDiscover feature transmits requests over unencrypted Hypertext Transfer Protocol (HTTP). A network attacker monitoring traffic can intercept these plaintext requests, exposing the user's entered credentials and leading to unauthorized account access.
Statement
This vulnerability is rated as having Moderate impact by Red Hat because credential exposure is restricted to the initial account setup phase for Exchange mailboxes, rather than affecting ongoing mail communication. Exploitation requires an attacker to be positioned on the local network path to eavesdrop on unencrypted traffic while a user performs automated configuration. Pre-existing email profiles and accounts configured for standard IMAP or POP3 protocols are not exposed to this flaw.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 5.3 | N/A | 5.9 |
| Attack Vector | Network | N/A | Network |
| Attack Complexity | High | N/A | High |
| Privileges Required | None | N/A | None |
| User Interaction | Required | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | High | N/A | High |
| Integrity Impact | None | N/A | None |
| Availability Impact | None | N/A | None |
Vector
Red Hat: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:N/A:N
cve.org: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
Understanding the Weakness (CWE)
Access Control
Technical Impact: Gain Privileges or Assume Identity
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