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CVE-2025-52887: Memory Exhaustion Vulnerability in cpp-httplib

Overview

The cybersecurity vulnerability CVE-2025-52887 is a high-risk flaw found within the cpp-httplib library, specifically in version 0.21.0. This C++11 single-file header-only cross platform HTTP/HTTPS library fails to limit the number of headers when multiple HTTP headers fields are passed in, leading to potential memory exhaustion and consequential system crash or unresponsiveness. This vulnerability matters tremendously as it could lead to system compromise or data leakage.

Vulnerability Summary

CVE ID: CVE-2025-52887
Severity: High (7.5 CVSS score)
Attack Vector: Network
Privileges Required: None
User Interaction: None
Impact: Potential system compromise or data leakage through memory exhaustion leading to server crashes or unresponsiveness.

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Product | Affected Versions

cpp-httplib | 0.21.0

How the Exploit Works

The exploit works by sending numerous HTTP header fields to a server running the cpp-httplib library version 0.21.0. This library does not limit the number of headers it accepts, and it also fails to release the memory associated with these headers once the connection is disconnected. This can lead to system memory exhaustion and subsequently, server crashes or unresponsiveness, potentially leading to system compromise or data leakage.

Conceptual Example Code

The vulnerability might be exploited using a large number of HTTP header fields. Here is a conceptual example of an HTTP request that might exploit this vulnerability:

POST /vulnerable/endpoint HTTP/1.1
Host: target.example.com
Content-Type: application/json
Header1: data
Header2: data
...
HeaderN: data
{ "payload": "..." }

In the above example, `Header1` through `HeaderN` represent an excessive number of HTTP headers passed to the server. This overload can exhaust the server’s memory, leading to potential system compromise or data leakage.

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Disclaimer:

The information and code presented in this article are provided for educational and defensive cybersecurity purposes only. Any conceptual or pseudocode examples are simplified representations intended to raise awareness and promote secure development and system configuration practices.

Do not use this information to attempt unauthorized access or exploit vulnerabilities on systems that you do not own or have explicit permission to test.

Ameeba and its authors do not endorse or condone malicious behavior and are not responsible for misuse of the content. Always follow ethical hacking guidelines, responsible disclosure practices, and local laws.
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