Account password sent unencrypted during Exchange account setup

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-113866
StatePUBLISHED
Assignermozilla
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-10-20 20:17:19 UTC
Updated2026-10-20 20:17:19 UTC
DescriptionWhen 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.

Risk And Classification

Primary CVSS: v3.1 5.9 MEDIUM from ADP

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N

Problem Types: CWE-523 | CWE-523 CWE-523 Unprotected Transport of Credentials

VersionSourceTypeScoreSeverityVector
3.1ADPDECLARED5.9MEDIUMCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
3.1134c704f-9b21-4f2e-91b3-4a467353bcc0Secondary5.9MEDIUMCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
High
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
None

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Mozilla Thunderbird unaffected 153.5.1 153.* rpm Not specified
CNA Mozilla Thunderbird unaffected 158.0.1 * rpm Not specified

References

ReferenceSourceLinkTags
www.mozilla.org/security/advisories/mfsa2026-114 [email protected] www.mozilla.org
www.mozilla.org/security/advisories/mfsa2026-115 [email protected] www.mozilla.org
bugzilla.mozilla.org/show_bug.cgi [email protected] bugzilla.mozilla.org
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Vendor Comments And Credit

Discovery Credit

CNA: Magnus Melin (en)

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