CVE-2025-62168

A Information Disclosure vulnerability has been identified in the Squid web caching proxy. This flaw occurs when the application fails to properly redact sensitive Hypertext Transfer Protocol (HTTP) authentication credentials from an error response. A remote client can exploit this by triggering an error condition, which allows a malicious script to bypass browser security and disclose the username and password a trusted client uses for access. This directly compromises the security of internal application credentials and security tokens, especially when Squid is configured for backend load balancing.

This vulnerability has rated as having the severity of Important by the Red Hat Product Security team as a successful exploitation may lead to sensitive information stored in the squid cache to be leaked, that may include authentication tokens for applications hosted behind the squid cache.

The leak happens due to squid cache not properly redacting request headers that may contain sensitive information out from error reports containing the request which triggered the error, resulting in a high confidentiality impact. The attacker does not need to have any kind of authentication to exploit this vulnerability.

To a squid instance to be considered vulnerable the email_err_data configuration may need to be turned on in the application configuration file. If the configuration entry is not present, the default behavior is to share such data letting the instance vulnerable.

The default behavior for squid in Red Hat Enterprise Linux distributions is to have email_err_data option enabled.

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.

This vulnerability can be mitigated by disabling debug information in administration mailto links generated by Squid package. This can be accomplished in Red Hat Enterprise Linux by the following steps:

1. With administrative privileges, edit the squid configuration file located at ~~~/etc/squid/squid.conf~~~
2. Add or change this configuration entry to: ~~~email_err_data off~~~
3. Save the configuration file
4. Restart the squid application