Improperly implemented security check for standard in firefox-esr (Alpine package)

Published: 2021-02-26
Risk Medium
Patch available YES
Number of vulnerabilities 1
CVE-ID CVE-2021-23969
Exploitation vector Network
Public exploit N/A
Vulnerable software
firefox-esr (Alpine package)
Operating systems & Components / Operating system package or component

Vendor Alpine Linux Development Team

Security Bulletin

This security bulletin contains one medium risk vulnerability.

1) Improperly implemented security check for standard

EUVDB-ID: #VU50879

Risk: Medium


CVE-ID: CVE-2021-23969

CWE-ID: CWE-358 - Improperly Implemented Security Check for Standard

Exploit availability: No


The vulnerability allows a remote attacker to bypass implemented security restrictions.

The vulnerability exists due to incorrect implementation of W3C Content Security Policy. Under certain types of redirects Firefox incorrectly sets the source file to be the destination of the redirects. A remote attacker can gain knowledge of the destination URL.


Install update from vendor's website.

Vulnerable software versions

firefox-esr (Alpine package): 60.4.0-r0 - 78.7.1-r0

CPE2.3 External links

Q & A

Can this vulnerability be exploited remotely?

Is there known malware, which exploits this vulnerability?