CVE-2020-12387
Mozilla: Use-after-free during worker shutdown
Severity
CriticalRed Hat Product Security
CVSS 3.0
Review impact separately from score.
Published · May 5, 2020
Updated · November 22, 2025
Description
A flaw was found in Mozilla Firefox and Thunderbird. When running shutdown code for Web Worker, a race condition occurs leading to a use-after-free memory flaw that could lead to an exploitable crash. The highest threat from this vulnerability is to data confidentiality and integrity as well as system availability.
CVSS score applicability
The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.
Mitigation
No mitigation is specified in collected source.
CVSS / CWE
CVSS 3.0 · 8.8CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
CWE-416 · Use After Free