Latest Squid caching proxy vulnerabilities #
Squid has disclosed a heap-based buffer overflow vulnerability in certain versions of the Squid caching proxy due to incorrect buffer management when processing a Uniform Resource Name (URN). This vulnerability allows a remote server to perform a buffer overflow attack by delivering specially crafted URN Trivial-HTTP responses. Successful exploitation may lead to remote code execution (RCE) or the disclosure of up to 4KB of data from Squid’s allocated heap memory. This leaked memory may contain security credentials or other confidential data. This vulnerability has been designated CVE-2025-54574 and has been rated critical with a CVSS score of 9.3.
The following versions are affected
- Squid 2.x versions up to and including 2.7.STABLE9
- Squid 3.x versions up to and including 3.5.28
- Squid 4.x versions up to and including 4.17
- Squid 5.x versions up to and including 5.9
- Squid 6.x versions up to and including 6.3
What is the impact? #
Successful exploitation of the vulnerability would allow an adversary to execute arbitrary code on the vulnerable host, potentially leading to complete system compromise.
Are updates or workarounds available? #
Users are encouraged to update to the latest version as quickly as possible:
- Squid 6.x upgrade to version 6.4 or later
- For all other stable releases upgrade to the latest patch version available in the patch archives
If you are using a prepackaged version of Squid, refer to your package vendor for information on the availability of updated packages.
Workaround: Mitigate the vulnerability by disabling URN access permissions through adding the following configuration changes:
acl URN proto URN
http_access deny URNHow to find potentially vulnerable systems with runZero #
From the Software Inventory, use the following query to locate potentially impacted assets:
vendor:"Squid Cache" and product:"Squid" and version:<6.4About runZero
runZero, a network discovery and asset inventory solution, was founded in 2018 by HD Moore, the creator of Metasploit. HD envisioned a modern active discovery solution that could find and identify everything on a network–without credentials. As a security researcher and penetration tester, he often employed benign ways to get information leaks and piece them together to build device profiles. Eventually, this work led him to leverage applied research and the discovery techniques developed for security and penetration testing to create runZero.
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