Remote code execution in Mozilla Firefox

Published: 2021-05-05
Risk High
Patch available YES
Number of vulnerabilities 1
CVE ID CVE-2021-29952
Exploitation vector Network
Public exploit N/A
Vulnerable software
Mozilla Firefox
Client/Desktop applications / Web browsers

Vendor Mozilla

Security Advisory

This security advisory describes one high risk vulnerability.

1) Race condition

Risk: High

CVSSv3.1: 7.7 [CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C] [PCI]

CVE-ID: CVE-2021-29952

CWE-ID: CWE-362 - Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')

Exploit availability: No


The vulnerability allows a remote attacker to compromise the affected system.

The vulnerability exists due to a race condition in Web Render components. A remote attacker can create a specially crafted web page, trick the victim into opening it and execute arbitrary code on the system.


Install updates from vendor's website.

Vulnerable software versions

Mozilla Firefox: 80.0, 80.0.1, 81.0, 81.0.1, 81.0.2, 82.0, 82.0.1, 82.0.2, 82.0.3, 83.0, 84.0, 84.0.1, 84.0.2, 85.0, 85.0.1, 85.0.2, 86.0, 86.0.1, 87.0, 88.0

CPE External links

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

How the attacker can exploit this vulnerability?

The attacker would have to trick the victim to visit a specially crafted website.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.