CVE-2017-5416: Mozilla Firefox

High severity, CVSS 7.5. EPSS: 1.8% chance of exploitation in the next 30 days.

In certain circumstances a networking event listener can be prematurely released. This appears to result in a null dereference in practice. This vulnerability affects Firefox < 52 and Thunderbird < 52.

Affected products

• Mozilla Firefox: before 52.0 (fixed in 52.0)
• Mozilla Thunderbird: before 52.0 (fixed in 52.0)

Published 2018-06-11. Last modified 2026-06-17.