CVE-2019-9805: Mozilla Firefox

Critical severity, CVSS 9.8. EPSS: 1.4% chance of exploitation in the next 30 days.

A latent vulnerability exists in the Prio library where data may be read from uninitialized memory for some functions, leading to potential memory corruption. This vulnerability affects Firefox < 66.

Affected products

• Mozilla Firefox: before 66.0 (fixed in 66.0)

Published 2019-04-26. Last modified 2026-06-17.