Squid <=6.5 DoS via Expired Pointer in Cache Manager
CVE-2024-23638 Published on January 24, 2024
SQUID-2023:11 Denial of Service in Cache Manager
Squid is a caching proxy for the Web. Due to an expired pointer reference bug, Squid prior to version 6.6 is vulnerable to a Denial of Service attack against Cache Manager error responses. This problem allows a trusted client to perform Denial of Service when generating error pages for Client Manager reports. Squid older than 5.0.5 have not been tested and should be assumed to be vulnerable. All Squid-5.x up to and including 5.9 are vulnerable. All Squid-6.x up to and including 6.5 are vulnerable. This bug is fixed by Squid version 6.6. In addition, patches addressing this problem for the stable releases can be found in Squid's patch archives. As a workaround, prevent access to Cache Manager using Squid's main access control: `http_access deny manager`.
Vulnerability Analysis
CVE-2024-23638 is exploitable with network access, and requires small amount of user privileges. This vulnerability is considered to have a low attack complexity. Public availability of a proof of concept (POC) exploit exists for CVE-2024-23638. The potential impact of an exploit of this vulnerability is considered to have no impact on confidentiality and integrity, and a high impact on availability.
Weakness Type
What is a Dangling pointer Vulnerability?
The program dereferences a pointer that contains a location for memory that was previously valid, but is no longer valid. When a program releases memory, but it maintains a pointer to that memory, then the memory might be re-allocated at a later time. If the original pointer is accessed to read or write data, then this could cause the program to read or modify data that is in use by a different function or process. Depending on how the newly-allocated memory is used, this could lead to a denial of service, information exposure, or code execution.
CVE-2024-23638 has been classified to as a Dangling pointer vulnerability or weakness.
Products Associated with CVE-2024-23638
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Affected Versions
squid-cache squid Version < 6.6 is affected by CVE-2024-23638Exploit Probability
EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.