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CVE-2025-3522
published 2025-04-15

CVE-2025-3522: Thunderbird processes the X-Mozilla-External-Attachment-URL header to handle attachments which can be hosted externally. When an email is opened, Thunderbird…

medium6.3CVSS 3.1
AVNACLPRNUIRSUCLILAL
Thunderbird 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.

Affected

8 ranges
VendorProductVersion rangeFixed in
debianthunderbird< thunderbird 1:128.10.0esr-1~deb12u1 (bookworm)thunderbird 1:128.10.0esr-1~deb12u1 (bookworm)
mozillafirefox
mozillathunderbird< 128.9.2128.9.2
mozillathunderbird>= 0 < 1:128.10.1esr-1~deb11u11:128.10.1esr-1~deb11u1
mozillathunderbird>= 0 < 1:128.10.0esr-1~deb12u11:128.10.0esr-1~deb12u1
mozillathunderbird>= 0 < 1:128.10.0esr-11:128.10.0esr-1
mozillathunderbird>= 0 < 1:128.10.0esr-11:128.10.0esr-1
mozillathunderbird>= 129.0 < 137.0.2137.0.2

CVSS provenance

nvdv3.16.3MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:L
osv6.3MEDIUM