CVE-2020-15666
MediumCVSS 6.5Exploitation Probability (EPSS)
Elevated risk67th percentile - higher than 67% of all known CVEs
Summary
Vulnerability in Firefox (and Firefox for Android) before version 80. When trying to load a non-video in an audio/video context, the exact status code (e.g., 200, 302, 404, 500) is disclosed via the MediaError message. This information leakage may allow inferring login status to services or device discovery on a local network.
Risk Assessment
Disclosure of detailed status codes may help an attacker in network or service reconnaissance, facilitating further attacks.
Recommendation
Update Firefox to version 80 or later.
Other vulnerabilities in Firefox
See all- CVE-2026-75874Critical
Sandbox escape in the Remote Settings Client component. This vulnerability was fixed in Firefox 154 and Thunderbird 154.
- CVE-2026-74990Critical
Internally found bugs in Firefox ESR 115.38, Firefox ESR 140.13, Firefox ESR 153.0 and Firefox 153. Some of these bugs showed evidence of memory corruption or another security-relevant defect and we presume that with enough effort some of these could have been exploited. This vulnerability was fixed in Firefox 154, Firefox ESR 115.39, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.
- CVE-2026-74989Critical
Internally found bugs in Firefox 153. Some of these bugs showed evidence of memory corruption or another security-relevant defect and we presume that with enough effort some of these could have been exploited. This vulnerability was fixed in Firefox 154 and Thunderbird 154.
- CVE-2026-74988Critical
Internally found bugs in Firefox ESR 153.0 and Firefox 153. Some of these bugs showed evidence of memory corruption or another security-relevant defect and we presume that with enough effort some of these could have been exploited. This vulnerability was fixed in Firefox 154, Firefox ESR 153.1, Thunderbird 154, and Thunderbird 153.1.
- CVE-2026-74987Critical
Internally found bugs in Firefox ESR 140.13, Firefox ESR 153.0 and Firefox 153. Some of these bugs showed evidence of memory corruption or another security-relevant defect and we presume that with enough effort some of these could have been exploited. This vulnerability was fixed in Firefox 154, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.
- CVE-2026-74986Critical
Site isolation issue in the CSS Parsing and Computation component. This vulnerability was fixed in Firefox 154, Firefox ESR 153.1, Thunderbird 154, and Thunderbird 153.1.
- CVE-2026-74985Critical
Privilege escalation in the Enterprise Policies component. This vulnerability was fixed in Firefox 154, Firefox ESR 153.1, Thunderbird 154, and Thunderbird 153.1.
- CVE-2026-74979Critical
Mitigation bypass in the Add-ons Manager component. This vulnerability was fixed in Firefox 154, Firefox ESR 153.1, Thunderbird 154, and Thunderbird 153.1.
- CVE-2026-74964Critical
Integer overflow in the Graphics component. Fixed in Firefox 154, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.
- CVE-2026-74961Critical
Side-channel vulnerability in the Web Audio component. Fixed in Firefox 154, Firefox ESR 153.1, Thunderbird 154, and Thunderbird 153.1.
Original NVD description (English source)
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.