Mozilla Thunderbird up to 153/153.1 Calendar Invitation code injection

Summaryinfo

A vulnerability was found in Mozilla Thunderbird up to 153/153.1. It has been declared as critical. The affected element is an unknown function of the component Calendar Invitation. Executing a manipulation can lead to code injection. This vulnerability is tracked as CVE-2026-84637. The attack can be launched remotely. No exploit exists.

Detailsinfo

A vulnerability was found in Mozilla Thunderbird up to 153/153.1. It has been declared as critical. This vulnerability affects some unknown processing of the component Calendar Invitation. The manipulation with an unknown input leads to a code injection vulnerability. The CWE definition for the vulnerability is CWE-94. The product constructs all or part of a code segment using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the syntax or behavior of the intended code segment. As an impact it is known to affect confidentiality, integrity, and availability. CVE summarizes:

Malicious calendar invitations could use file URI attachments to launch local or network-hosted executables on Windows, bypassing Thunderbird's normal executable attachment protections. With the new invitation display enabled, the attachment could also appear under a misleading filename. This vulnerability was fixed in Thunderbird 154 and Thunderbird 153.2.

The advisory is available at bugzilla.mozilla.org. This vulnerability was named CVE-2026-84637 since 09/01/2026. The exploitation appears to be easy. The attack can be initiated remotely. Successful exploitation requires user interaction by the victim. The technical details are unknown and an exploit is not available. The structure of the vulnerability defines a possible price range of USD $5k-$25k at the moment (estimation calculated on 09/01/2026). This vulnerability is assigned to T1059 by the MITRE ATT&CK project.

Upgrading to version 153.2 or 154 eliminates this vulnerability.

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Productinfo

Type

• Mail Client Software

Vendor

• Mozilla

Name

• Thunderbird

Version

• 153
• 153.0
• 153.1

License

• open-source

Website

• Vendor: https://www.mozilla.org/

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