CVE-2017-7800: Debian Linux

Critical severity, CVSS 9.8. EPSS: 3% chance of exploitation in the next 30 days.

A use-after-free vulnerability can occur in WebSockets when the object holding the connection is freed before the disconnection operation is finished. This results in an exploitable crash. This vulnerability affects Thunderbird < 52.3, Firefox ESR < 52.3, and Firefox < 55.

Affected products

• Debian Debian Linux: version 8.0 only; version 9.0 only
• Mozilla Firefox: before 55.0 (fixed in 55.0); before 52.3.0 (fixed in 52.3.0)
• Mozilla Thunderbird: before 52.3.0 (fixed in 52.3.0)
• Red Hat Enterprise Linux: version 6.0 only; version 7.0 only
• Red Hat Enterprise Linux Desktop: version 6.0 only; version 7.0 only
• Red Hat Enterprise Linux Server: version 6.0 only; version 7.0 only
• Red Hat Enterprise Linux Server Aus: version 7.3 only; version 7.4 only
• Red Hat Enterprise Linux Server Eus: version 7.3 only; version 7.4 only; version 7.5 only
• Red Hat Enterprise Linux Workstation: version 6.0 only; version 7.0 only

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