Leak of hashed Window credentials via crafted attachment URL

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Summary

CVECVE-2025-3522
StatePUBLISHED
Assignermozilla
Source PriorityCVE Program / NVD first with legacy fallback
Published2025-04-15 15:16:09 UTC
Updated2026-04-13 15:16:57 UTC
DescriptionThunderbird processes the X-Mozilla-External-Attachment-URL header to handle attachments which can be hosted externally. When an email is opened, Thunderbird accesses the specified URL to determine file size, and navigates to it when the user clicks the attachment. Because the URL is not validated or sanitized, it can reference internal resources like chrome:// or SMB share file:// links, potentially leading to hashed Windows credential leakage and opening the door to more serious security issues. This vulnerability was fixed in Thunderbird 137.0.2 and Thunderbird 128.9.2.

Risk And Classification

Primary CVSS: v3.1 6.3 MEDIUM from ADP

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

Problem Types: CWE-601 | CWE-601 CWE-601 URL Redirection to Untrusted Site ('Open Redirect')

VersionSourceTypeScoreSeverityVector
3.1ADPDECLARED6.3MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:L
3.1134c704f-9b21-4f2e-91b3-4a467353bcc0Secondary6.3MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:L

CVSS v3.1 Breakdown

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

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

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Application Mozilla Thunderbird All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Mozilla Thunderbird unaffected 128.9.2 128.* rpm Not specified
CNA Mozilla Thunderbird unaffected 137.0.2 * rpm Not specified

References

ReferenceSourceLinkTags
www.mozilla.org/security/advisories/mfsa2025-27 [email protected] www.mozilla.org Vendor Advisory
www.mozilla.org/security/advisories/mfsa2025-26 [email protected] www.mozilla.org Vendor Advisory
bugzilla.mozilla.org/show_bug.cgi [email protected] bugzilla.mozilla.org Permissions Required
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: Dario Weißer (en)

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