Squid Cache Manager Access Bypass Vulnerability in Squid 4.7
Summary
CVE-2019-12524: An issue was discovered in Squid through 4.7. Affects squid across 2 version ranges.
< 2e17b02616d37206ba9cccc53c20667624fbef9f
< 4.8-1
Fixed in 4.8-1. How to fix ↓
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Background
Squid is a widely used caching proxy for the web that supports HTTP, HTTPS, FTP, and more. It is designed to improve web performance by caching frequently requested content and reducing bandwidth usage. Squid also provides access control features to manage user requests. However, a vulnerability was discovered in version 4.7 that allows attackers to bypass access controls intended to protect sensitive server information.
Vulnerability Detail
The vulnerability arises from the way Squid handles requests using url_regex rules. When processing incoming requests, Squid decodes URLs, which can be exploited by attackers. By encoding their URLs in a specific manner, an attacker can bypass the default rules that block access to the Cache Manager, potentially exposing sensitive server information. This could lead to unauthorized access and exploitation of the server's configuration and status.
How To Fix
Minimum fixed version
4.8-1
This is the first release that contains the fix.
sudo apt-get install --only-upgrade squidTip — Not sure which version your app runs? Vulert can match this fix to it. Scan free →
Workaround
As a temporary workaround, administrators can modify the Squid configuration to tighten access controls or restrict access to the Cache Manager by implementing additional security measures, such as IP whitelisting or using authentication mechanisms.
Conclusion
The Squid vulnerability CVE-2019-12524 poses a significant risk by allowing attackers to bypass access controls to the Cache Manager. It is crucial for users of Squid to upgrade to version 4.8-1 or later to mitigate this risk. Additionally, implementing workarounds can provide temporary relief until the upgrade is completed.
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FAQ
The CVSS score of this vulnerability is 9.8, indicating a critical level of severity.
Versions of Squid prior to 4.8-1 are affected by this vulnerability.
You can use the Vulert playground at Vulert Scanner to check if your application is affected by this vulnerability without needing to sign up.
If exploited, this vulnerability could allow unauthorized users to access sensitive server information, potentially leading to further attacks or data breaches.
Yes, Vulert can monitor and alert you in real-time for open-source vulnerabilities in your software using just a manifest file like package-lock.json.
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