Squid vulnerable to information disclosure via authentication credential leakage in error handling

Vulnerability Description

Squid is a caching proxy for the Web. In Squid versions prior to 7.2, a failure to redact HTTP authentication credentials in error handling allows information disclosure. The vulnerability allows a script to bypass browser security protections and learn the credentials a trusted client uses to authenticate. This potentially allows a remote client to identify security tokens or credentials used internally by a web application using Squid for backend load balancing. These attacks do not require Squid to be configured with HTTP authentication. The vulnerability is fixed in version 7.2. As a workaround, disable debug information in administrator mailto links generated by Squid by configuring squid.conf with email_err_data off.

References

• https://github.com/squid-cache/squid/security/advisories/GHSA-c8cc-phh7-xmxr
• https://github.com/squid-cache/squid/commit/0951a0681011dfca3d78c84fd7f1e19c78a4443f