Mozilla Thunderbird up to 153.5/158 OpenPGP information disclosure

Summaryinfo

A vulnerability has been found in Mozilla Thunderbird up to 153.5/158 and classified as problematic. This impacts an unknown function of the component OpenPGP. The manipulation leads to information disclosure. This vulnerability is referenced as CVE-2026-118174. Remote exploitation of the attack is possible. No exploit is available. The affected component should be upgraded.

Detailsinfo

A vulnerability was found in Mozilla Thunderbird up to 153.5/158. It has been rated as problematic. This issue affects an unknown part of the component OpenPGP. The manipulation with an unknown input leads to a information disclosure vulnerability. Using CWE to declare the problem leads to CWE-200. The product exposes sensitive information to an actor that is not explicitly authorized to have access to that information. Impacted is confidentiality. The summary by CVE is:

When a message containing an OpenPGP key attachment was displayed, Thunderbird automatically loaded the attachment's content to offer importing the key. A sender could mark the attachment as an external attachment pointing to an arbitrary URL, which Thunderbird then loaded without any user interaction, bypassing remote content blocking. On Windows, a URL pointing to an attacker-controlled network share could leak the user's NTLM credentials. The NTLM credential leak only affects Thunderbird on Windows. On other operating systems, the issue allowed a remote request that bypassed remote content blocking. This vulnerability was fixed in Thunderbird 159 and Thunderbird 153.6.

It is possible to read the advisory at bugzilla.mozilla.org. The identification of this vulnerability is CVE-2026-118174 since 10/27/2026. The exploitation is known to be easy. The attack may be initiated remotely. The technical details are unknown and an exploit is not publicly available. The pricing for an exploit might be around USD $0-$5k at the moment (estimation calculated on 10/28/2026). The attack technique deployed by this issue is T1592 according to MITRE ATT&CK.

The vulnerability scanner Nessus provides a plugin with the ID 372632 (Mozilla Thunderbird < 153.6), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 153.6 or 159 eliminates this vulnerability.

The vulnerability is also documented in the vulnerability database at Tenable (372632). Be aware that VulDB is the high quality source for vulnerability data.

Productinfo

Type

• Mail Client Software

Vendor

• Mozilla

Name

• Thunderbird

Version

• 153.0
• 153.1
• 153.2
• 153.3
• 153.4
• 153.5
• 158

License

• open-source

Website

• Vendor: https://www.mozilla.org/

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Be aware that VulDB is the high quality source for vulnerability data.

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