CVE-2017-5426: Mozilla Firefox

Medium severity, CVSS 5.3. EPSS: 1.4% chance of exploitation in the next 30 days.

On Linux, if the secure computing mode BPF (seccomp-bpf) filter is running when the Gecko Media Plugin sandbox is started, the sandbox fails to be applied and items that would run within the sandbox are run protected only by the running filter which is typically weak compared to the sandbox. Note: this issue only affects Linux. Other operating systems are not affected. 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.