SB2021100402 - Multiple vulnerabilities in Squid

Description

This security bulletin contains information about 2 secuirty vulnerabilities.

1) Improper Certificate Validation (CVE-ID: CVE-2021-41611)

The vulnerability allows a remote attacker to perform a MitM attack.

The vulnerability exists due to improper certificate validation when the TLS server certificate is signed by multiple CAs. A remote attacker can perform a mand-in-the-middle attack against proxy server users.

2) Out-of-bounds read (CVE-ID: CVE-2021-28116)

The vulnerability allows a remote attacker to gain access to potentially sensitive information.

The vulnerability exists due to a boundary condition within the handling of the WCCP protocol. A remote attacker can send specially crafted data and corrupt Squids list of known WCCP routers and divert client traffic to attacker controlled routers.

This attack is limited to Squid proxy with WCCPv2 enabled and IP spoofing of a router IP address configured as trusted in squid.conf.

Remediation

Install update from vendor's website.

References

• https://github.com/squid-cache/squid/security/advisories/GHSA-47m4-g3mv-9q5r/
• https://www.zerodayinitiative.com/advisories/ZDI-21-157/
• https://github.com/squid-cache/squid/security/advisories/GHSA-rgf3-9v3p-qp82/