CVE-2023-46847 is a classic buffer overflow vulnerability identified in Squid version 3.2.0.1, specifically when configured to accept HTTP Digest Authentication. The vulnerability arises from a failure to properly check the size of input data before copying it into heap memory, allowing a remote attacker to write up to 2 megabytes of arbitrary data. This unchecked buffer copy can lead to heap corruption and ultimately cause a Denial of Service (DoS) by crashing the Squid process or destabilizing the proxy service. The attack vector is network-based, requiring no privileges or user interaction, making it highly accessible to remote attackers. The CVSS v3.1 base score of 8.6 reflects the high impact on availability and moderate impact on confidentiality and integrity, as the overflow could potentially be leveraged for further exploitation, though no such exploits are currently known. Squid is widely used as a caching proxy and web accelerator in enterprise and ISP environments, often deployed in front of web servers or as part of security architectures. The vulnerability’s exploitation could disrupt web traffic, degrade service quality, and impact dependent applications. No official patches or mitigations are linked in the provided data, but standard practice would involve applying vendor patches or disabling HTTP Digest Authentication to mitigate risk. The vulnerability was published on November 3, 2023, and assigned by Red Hat, indicating recognition by major Linux distributors. Given the age of the affected version (3.2.0.1), organizations running legacy Squid deployments are particularly vulnerable.

For European organizations, the primary impact of CVE-2023-46847 is the potential for Denial of Service attacks against critical proxy infrastructure. Many enterprises, government agencies, and ISPs in Europe rely on Squid proxies for caching, content filtering, and access control. A successful attack could cause service outages, interrupting web access and internal communications, leading to operational disruptions and potential financial losses. The vulnerability also poses a risk to confidentiality and integrity, albeit lower, as heap corruption could be a stepping stone for more advanced exploits. Organizations in sectors such as finance, healthcare, telecommunications, and public administration are particularly at risk due to their reliance on stable and secure proxy services. Additionally, disruption of proxy services could impact compliance with data protection regulations like GDPR if service availability affects data processing or access controls. The lack of known exploits in the wild reduces immediate risk but does not eliminate the threat, especially as attackers may develop exploits given the public disclosure. The ease of remote exploitation without authentication increases the urgency for European organizations to assess and remediate vulnerable Squid instances.

1. Immediately identify all Squid proxy instances running version 3.2.0.1 or other vulnerable versions within the network, especially those configured with HTTP Digest Authentication enabled. 2. Apply vendor-provided patches or upgrade to the latest supported Squid version where this vulnerability is fixed. If no official patch is available, consider upgrading to a newer, supported release branch. 3. If patching is not immediately possible, disable HTTP Digest Authentication on Squid proxies to eliminate the attack vector. 4. Implement network-level protections such as firewall rules to restrict access to Squid proxy ports from untrusted networks. 5. Monitor proxy logs and network traffic for unusual patterns indicative of buffer overflow attempts or anomalous large HTTP Digest Authentication payloads. 6. Conduct regular vulnerability scans and penetration tests focusing on proxy services to detect potential exploitation attempts. 7. Develop incident response plans specifically addressing proxy service outages and potential DoS scenarios. 8. Educate IT and security teams about this vulnerability and ensure timely communication of updates from Squid maintainers or Linux distributors. 9. Consider deploying application-layer firewalls or intrusion prevention systems capable of detecting malformed HTTP Digest Authentication requests. 10. Maintain an inventory of legacy systems and plan migration away from unsupported Squid versions to reduce future risk.