CVE-2023-49286 – Squid caching proxy versions before 6.5 contain... (How to Fix)

Q: What is the severity of CVE-2023-49286?

CVE-2023-49286 has a CVSS score of 8.6 (HIGH). Squid caching proxy versions before 6.5 contain an incorrect check of function return value bug in helper process management that allows denial of service attacks. Attackers can crash Squid's helper processes, disrupting proxy services. All Squid deployments using affected versions are vulnerable.

📋 TL;DR

Squid caching proxy versions before 6.5 contain an incorrect check of function return value bug in helper process management that allows denial of service attacks. Attackers can crash Squid's helper processes, disrupting proxy services. All Squid deployments using affected versions are vulnerable.

💻 Affected Systems

Products:

Squid caching proxy

Versions: All versions before 6.5

Operating Systems: All operating systems running Squid

Default Config Vulnerable: ⚠️ Yes

Notes: All Squid configurations using helper processes are affected. Helper processes are commonly used for authentication, URL filtering, and other extensions.

📦 What is this software?

Squid by Squid Cache

View all CVEs affecting Squid →

⚠️ Risk & Real-World Impact

🔴

Worst Case

Complete service disruption of Squid proxy, affecting all web traffic routing through it, potentially causing business operations to halt.

🟠

Likely Case

Intermittent proxy service crashes requiring manual restart, degrading performance and reliability of web access for users.

🟢

If Mitigated

Limited impact with monitoring and rapid restart capabilities, but still vulnerable to repeated attacks.

🌐 Internet-Facing: HIGH - Squid proxies are typically internet-facing and directly accessible to attackers.

🏢 Internal Only: MEDIUM - Internal attackers or compromised internal systems could exploit this vulnerability.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ⚠️ Yes

Complexity: LOW

The vulnerability is in helper process management and could be triggered by sending specially crafted requests to the proxy.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Squid 6.5

Vendor Advisory: https://github.com/squid-cache/squid/security/advisories/GHSA-xggx-9329-3c27

Restart Required: Yes

Instructions:

1. Download Squid 6.5 from squid-cache.org. 2. Stop Squid service. 3. Backup configuration. 4. Install new version. 5. Restart Squid service.

🔧 Temporary Workarounds

No workarounds available

all

The vendor advisory states there are no known workarounds for this vulnerability.

🧯 If You Can't Patch

Implement network segmentation to restrict access to Squid proxy from untrusted networks
Deploy additional monitoring and alerting for Squid service crashes with automated restart capabilities

🔍 How to Verify

Check if Vulnerable:

Check Squid version with 'squid -v' or 'squid -v | grep Version' and compare to 6.5

Check Version:

squid -v | grep Version

Verify Fix Applied:

After upgrade, verify version is 6.5 or later with 'squid -v' and test proxy functionality

📡 Detection & Monitoring

Log Indicators:

Unexpected helper process crashes
Squid service restarts
Error messages related to helper process management

Network Indicators:

Increased failed proxy requests
Unusual traffic patterns to Squid helper ports

SIEM Query:

source="squid" AND ("helper" OR "process" OR "crash")

📊 Metadata

CVE ID: CVE-2023-49286

CVSS v3 Score: 8.6 (HIGH)

CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H

CWE: CWE-253

Published: December 4, 2023

Last Updated: November 21, 2024

🔗 References

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