Missing Authentication for Critical Function in Squid - CVE-2019-12524
Published: May 11, 2020 / Updated: August 6, 2025
Vulnerability identifier: #VU27669
CSH Severity: Low
CVSSv4.0: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:U/U:Clear
CVE-ID: CVE-2019-12524
CWE-ID: CWE-306
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerable software:
Squid
Squid
Software vendor:
Squid-cache.org
Squid-cache.org
Description
The vulnerability allows a remote attacker to bypass certain security restrictions.
When handling requests from users, Squid checks its rules to see if the request should be denied. Squid by default comes with rules to block access to the Cache Manager, which serves detailed server information meant for the maintainer. This rule is implemented via url_regex. The handler for url_regex rules URL decodes an incoming request. This allows an attacker to encode their URL to bypass the url_regex check, and gain access to the blocked resource.
Remediation
Install updates from vendor's website.