CVE-2021-23976 Explained : Impact and Mitigation

A vulnerability in Firefox for Android, tracked as CVE-2021-23976, allowed malicious apps to manipulate webapp manifests, potentially enabling UI spoofing and cross-origin attacks.

Understanding CVE-2021-23976

This CVE impacts Firefox for Android versions prior to 86, enabling threat actors to spoof web manifests and launch local attacks.

What is CVE-2021-23976?

Firefox for Android permitted the acceptance of intents from other apps, allowing for the declaration of webapp manifests from arbitrary paths. This flaw facilitated fullscreen access for UI spoofing and cross-origin attacks.

The Impact of CVE-2021-23976

The vulnerability only affected Firefox for Android, posing a risk of local spoofing of web manifests for arbitrary pages, affecting versions below 86.

Technical Details of CVE-2021-23976

The vulnerability in Firefox for Android stemmed from accepting malicious intents from external apps, leading to the misuse of webapp manifests for unauthorized actions.

Vulnerability Description

By accepting manifests from arbitrary file paths, threat actors could gain access to fullscreen mode for UI spoofing and carry out cross-origin attacks on specific websites.

Affected Systems and Versions

Firefox for Android versions below 86 were impacted by this vulnerability, while other operating systems remained unaffected.

Exploitation Mechanism

Threat actors could exploit this vulnerability by manipulating webapp manifests from various file paths, enabling them to perform UI spoofing and launch cross-origin attacks.

Mitigation and Prevention

To safeguard against CVE-2021-23976, users should take immediate steps and adopt long-term security measures.

Immediate Steps to Take

Users are advised to update Firefox for Android to version 86 or higher to mitigate this vulnerability. Additionally, exercise caution when interacting with unknown or untrusted apps.

Long-Term Security Practices

Maintain regular software updates, implement security patches promptly, and avoid granting unnecessary permissions to applications to reduce the risk of similar exploits.

Patching and Updates

Mozilla has released patches addressing CVE-2021-23976. Users should apply the latest updates to ensure their systems are protected against potential threats.