CVE-2021-38505 : What You Need to Know

This CVE-2021-38505 involves a vulnerability in Microsoft's Windows 10 Cloud Clipboard feature that impacted Mozilla's Firefox, Thunderbird, and Firefox ESR. When enabled, Cloud Clipboard recorded copied data to the cloud, potentially exposing sensitive information to a user's Microsoft account.

Understanding CVE-2021-38505

This vulnerability arises from a lack of implementation of specific clipboard formats in Firefox versions prior to 94 and ESR 91.3, allowing data leakage when Cloud Clipboard is active only on Windows 10+ systems.

What is CVE-2021-38505?

Microsoft's Cloud Clipboard feature in Windows 10 inadvertently recorded sensitive user data from Firefox, Thunderbird, and Firefox ESR due to missing clipboard format implementation in older versions of these applications.

The Impact of CVE-2021-38505

The vulnerability could have led to the inadvertent exposure of sensitive user data copied to the clipboard in Firefox, Thunderbird, and Firefox ESR to the user's Microsoft account when Cloud Clipboard was enabled specifically on Windows 10+ systems.

Technical Details of CVE-2021-38505

This section delves into the specifics of the vulnerability affecting the Mozilla applications.

Vulnerability Description

Firefox, Thunderbird, and Firefox ESR versions earlier than 94 and 91.3 respectively did not implement specific clipboard formats, allowing Cloud Clipboard to record sensitive information to the user's Microsoft account.

Affected Systems and Versions

The vulnerability impacted Firefox versions below 94, Thunderbird versions below 91.3, and Firefox ESR versions below 91.3.

Exploitation Mechanism

The exploitation involves bypassing the lack of clipboard format protection in older versions of Firefox, Thunderbird, and Firefox ESR when Cloud Clipboard is enabled on Windows 10+ systems.

Mitigation and Prevention

To address the CVE-2021-38505 vulnerability, users are advised to take immediate steps and adopt long-term security practices.

Immediate Steps to Take

Users should update their Firefox, Thunderbird, and Firefox ESR to versions 94, 91.3, or later to prevent sensitive data exposure through Cloud Clipboard.

Long-Term Security Practices

It is recommended to disable Cloud Clipboard or use alternative clipboard managers that ensure data security across platforms.

Patching and Updates

Regularly check for security updates from Mozilla to patch vulnerabilities and protect against potential data leakage through features like Cloud Clipboard.