CVE-2020-12393: Mozilla Firefox

High severity, CVSS 7.8. EPSS: 1% chance of exploitation in the next 30 days.

The 'Copy as cURL' feature of Devtools' network tab did not properly escape the HTTP method of a request, which can be controlled by the website. If a user used the 'Copy as cURL' feature and pasted the command into a terminal, it could have resulted in command injection and arbitrary command execution. *Note: this issue only affects Firefox on Windows operating systems.*. This vulnerability affects Firefox ESR < 68.8, Firefox < 76, and Thunderbird < 68.8.0.

Affected products

• Mozilla Firefox: before 76.0 (fixed in 76.0)
• Mozilla Firefox ESR: before 68.8.0 (fixed in 68.8.0)
• Mozilla Thunderbird: before 68.8.0 (fixed in 68.8.0)

Published 2020-05-26. Last modified 2026-06-17.