CVE-2022-41317: Squid-cache Information Disclosure Flaw

CVE-2022-41317 Overview

CVE-2022-41317 is an information disclosure vulnerability affecting Squid proxy server versions 4.9 through 4.17 and 5.0.6 through 5.6. The vulnerability stems from inconsistent handling of internal URIs, which can result in the exposure of sensitive information about clients using the proxy. An authenticated attacker can exploit this flaw by sending HTTPS requests to internal cache manager URLs, potentially accessing confidential client data that should be protected.

Critical Impact

Authenticated attackers can access sensitive client information through improperly handled internal cache manager URLs, potentially compromising client privacy and network security posture.

Affected Products

• Squid-cache Squid versions 4.9 through 4.17
• Squid-cache Squid versions 5.0.6 through 5.6
• Systems using vulnerable Squid versions as forward or reverse proxies

Discovery Timeline

• 2022-12-25 - CVE-2022-41317 published to NVD
• 2025-04-14 - Last updated in NVD database

Technical Details for CVE-2022-41317

Vulnerability Analysis

This vulnerability is classified under CWE-697 (Incorrect Comparison), indicating a fundamental flaw in how the Squid proxy handles comparisons when processing internal URIs. The inconsistent URI handling allows authenticated users to craft specific HTTPS requests targeting internal cache manager endpoints that would normally be restricted.

The cache manager in Squid provides diagnostic and administrative functions that can reveal detailed information about proxy operations, connected clients, and cache statistics. When internal URIs are processed inconsistently, requests that should be blocked or restricted may inadvertently pass through security checks, exposing sensitive data to unauthorized parties.

The attack requires network access and low-privilege authentication to the proxy service, but no user interaction is needed. While the vulnerability does not allow modification of data or service disruption, the potential for high-impact information disclosure makes it a significant security concern for organizations relying on Squid for their proxy infrastructure.

Root Cause

The root cause lies in CWE-697: Incorrect Comparison within the Squid proxy's URI handling logic. The internal URI processing mechanism fails to consistently apply security restrictions when comparing and routing requests to internal cache manager endpoints. This inconsistency creates a bypass where authenticated users can access internal management interfaces through HTTPS requests that circumvent normal access controls.

Attack Vector

The attack is network-based, requiring the attacker to have low-level authentication credentials on the target Squid proxy. The exploitation process involves:

1. An attacker authenticates to the Squid proxy with valid credentials
2. The attacker crafts an HTTPS request targeting internal cache manager URLs
3. Due to inconsistent URI handling, the request bypasses security restrictions
4. Sensitive information about other proxy clients is returned in the response

The vulnerability allows confidential data exposure without impacting the integrity or availability of the proxy service. The information disclosed may include client IP addresses, browsing patterns, cache contents, and other sensitive operational data managed by the cache manager.

Detection Methods for CVE-2022-41317

Indicators of Compromise

• Unusual HTTPS requests targeting internal cache manager URLs (e.g., /squid-internal-mgr/ endpoints)
• Authenticated users making repeated requests to administrative cache manager interfaces
• Access logs showing queries to cache manager endpoints from unexpected sources
• Anomalous patterns of cache manager access outside normal administrative operations

Detection Strategies

• Monitor Squid access logs for requests containing squid-internal-mgr or cache manager URL patterns
• Implement network monitoring to detect HTTPS traffic to internal management endpoints
• Review authentication logs for unusual activity patterns from authenticated proxy users
• Deploy SentinelOne endpoint detection to identify suspicious process behavior associated with exploitation attempts

Monitoring Recommendations

• Enable verbose logging on Squid proxy servers to capture detailed request information
• Configure alerting for access attempts to cache manager URLs from non-administrative accounts
• Implement network segmentation monitoring to detect lateral movement after information disclosure
• Regularly audit access control lists and authentication configurations for the cache manager

How to Mitigate CVE-2022-41317

Immediate Actions Required

• Upgrade Squid to version 5.7 or later, which contains the official fix for this vulnerability
• For Squid 4.x installations, apply the official patch from Squid Patch for v4
• For Squid 5.x installations prior to 5.7, apply the official patch from Squid Patch for v5
• Review cache manager access logs to identify any potential prior exploitation

Patch Information

The vulnerability has been fixed in Squid version 5.7. Organizations running affected versions should prioritize upgrading to this release or applying the appropriate patches. Official patches are available:

• Squid Patch for v4 - For Squid 4.9 through 4.17
• Squid Patch for v5 - For Squid 5.0.6 through 5.6

For detailed information about the vulnerability and remediation, refer to the GitHub Security Advisory and OpenWall OSS Security Discussion.

Workarounds

• Restrict cache manager access using ACLs to limit which users can query internal management URLs
• Implement network-level access controls to block external access to cache manager endpoints
• Consider disabling the cache manager feature if not required for operational purposes
• Use firewall rules to limit access to the Squid proxy management interface to trusted administrative networks only

# Squid ACL configuration to restrict cache manager access
# Add to squid.conf to limit cache manager to localhost only
acl manager url_regex -i ^cache_object:// +i ^https?://[^/]+/squid-internal-mgr/
acl localhost src 127.0.0.1/32 ::1
http_access allow manager localhost
http_access deny manager