CVE-2020-15666

When trying to load a non-video in an audio/video context the exact status code (200, 302, 404, 500, 412, 403, etc.) was disclosed via the MediaError Message. This level of information leakage is inconsistent with the standardized onerror/onsuccess disclosure and can lead to inferring login status to services or device discovery on a local network among other attacks. This vulnerability affects Firefox < 80 and Firefox for Android < 80.

Weakness

The product generates an error message that includes sensitive information about its environment, users, or associated data.

Affected Software

Potential Mitigations

• Ensure that error messages only contain minimal details that are useful to the intended audience and no one else. The messages need to strike the balance between being too cryptic (which can confuse users) or being too detailed (which may reveal more than intended). The messages should not reveal the methods that were used to determine the error. Attackers can use detailed information to refine or optimize their original attack, thereby increasing their chances of success.
• If errors must be captured in some detail, record them in log messages, but consider what could occur if the log messages can be viewed by attackers. Highly sensitive information such as passwords should never be saved to log files.
• Avoid inconsistent messaging that might accidentally tip off an attacker about internal state, such as whether a user account exists or not.

Related Attack Patterns

• https://cwe.mitre.org/data/definitions/215.html
• https://cwe.mitre.org/data/definitions/463.html
• https://cwe.mitre.org/data/definitions/54.html
• https://cwe.mitre.org/data/definitions/7.html

References

• https://bugzilla.mozilla.org/show_bug.cgi?id=1450853
• https://www.mozilla.org/security/advisories/mfsa2020-36/
• https://www.mozilla.org/security/advisories/mfsa2020-39/
• https://bugzilla.mozilla.org/show_bug.cgi?id=1450853
• https://www.mozilla.org/security/advisories/mfsa2020-36/
• https://www.mozilla.org/security/advisories/mfsa2020-39/