Detections
Analytics

Mozilla Thunderbird < 138.0.1

medium Nessus Plugin ID 236403

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Synopsis

A mail client installed on the remote macOS or Mac OS X host is affected by multiple vulnerabilities.

Description

The version of Thunderbird installed on the remote macOS or Mac OS X host is prior to 138.0.1. It is, therefore, affected by multiple vulnerabilities as referenced in the mfsa2025-35 advisory.

 - A crafted HTML email using mailbox:/// links can trigger automatic, unsolicited downloads of .pdf files to the user's desktop or home directory without prompting, even if auto-saving is disabled. This behavior can be abused to fill the disk with garbage data (e.g. using /dev/urandom on Linux) or to leak Windows credentials via SMB links when the email is viewed in HTML mode. While user interaction is required to download the .pdf file, visual obfuscation can conceal the download trigger. Viewing the email in HTML mode is enough to load external content. (CVE-2025-3877)

 - Thunderbird parses addresses in a way that can allow sender spoofing in case the server allows an invalid From address to be used. For example, if the From header contains an (invalid) value Spoofed Name <[email protected]> <[email protected]>, Thunderbird treats [email protected] as the actual address. (CVE-2025-3875)

 - Thunderbird's handling of the X-Mozilla-External-Attachment-URL header can be exploited to execute JavaScript in the file:/// context. By crafting a nested email attachment (message/rfc822) and setting its content type to application/pdf, Thunderbird may incorrectly render it as HTML when opened, allowing the embedded JavaScript to run without requiring a file download. This behavior relies on Thunderbird auto- saving the attachment to /tmp and linking to it via the file:/// protocol, potentially enabling JavaScript execution as part of the HTML. (CVE-2025-3909)

 - It was possible to craft an email that showed a tracking link as an attachment. If the user attempted to open the attachment, Thunderbird automatically accessed the link. The configuration to block remote content did not prevent that. Thunderbird has been fixed to no longer allow access to web pages listed in the X-Mozilla-External-Attachment-URL header of an email. (CVE-2025-3932)

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

Solution

Upgrade to Mozilla Thunderbird version 138.0.1 or later.

See Also

https://www.mozilla.org/en-US/security/advisories/mfsa2025-35/

Plugin Details

Severity: Medium

ID: 236403

File Name: macos_thunderbird_138_0_1.nasl

Version: 1.3

Type: local

Agent: macosx

Published: 5/14/2025

Updated: 5/29/2025

Supported Sensors: Nessus Agent, Nessus

Risk Information

VPR

Risk Factor: Medium

Score: 4.4

CVSS v2

Risk Factor: Medium

Base Score: 4.3

Temporal Score: 3.2

Vector: CVSS2#AV:N/AC:M/Au:N/C:P/I:N/A:N

CVSS Score Source: CVE-2025-3877

CVSS v3

Risk Factor: Medium

Base Score: 6.5

Temporal Score: 5.7

Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N

Temporal Vector: CVSS:3.0/E:U/RL:O/RC:C

Vulnerability Information

CPE: cpe:/a:mozilla:thunderbird

Required KB Items: MacOSX/Thunderbird/Installed

Exploit Ease: No known exploits are available

Patch Publication Date: 5/13/2025

Vulnerability Publication Date: 5/13/2025

Reference Information

CVE: CVE-2025-3875, CVE-2025-3877, CVE-2025-3909, CVE-2025-3932

IAVA: 2025-A-0357-S