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CVE-2025-53537: Severe Memory Leak Vulnerability in LibHTP

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Overview

This report details a significant vulnerability in LibHTP, a security-aware parser for the HTTP protocol. The vulnerability, referenced as CVE-2025-53537, affects versions 0.5.50 and below, allowing attackers to starve a process of memory, causing loss of visibility. This particular vulnerability carries significant implications for any entity using an affected LibHTP version, potentially leading to system compromise or data leakage.

Vulnerability Summary

CVE ID: CVE-2025-53537
Severity: High (7.5)
Attack Vector: Network
Privileges Required: None
User Interaction: None
Impact: Potential system compromise or data leakage

Affected Products

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Product | Affected Versions

LibHTP | 0.5.50 and below

How the Exploit Works

The CVE-2025-53537 vulnerability originates from a memory leak in LibHTP’s handling of HTTP traffic. If an attacker can generate sufficient traffic, it can starve the process of memory. This memory starvation can lead to a loss of visibility, which can potentially pave the way for further attacks and exploitation.

Conceptual Example Code

Though the specifics of the exploit are not public, an attacker might generate massive traffic to the target server to induce memory leak. A conceptual example of how this might be done is shown below:

POST / HTTP/1.1
Host: target.example.com
Content-Type: application/x-www-form-urlencoded
data=AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA...

This example sends a POST request with a large payload to the target server. An attacker might automate this and send multiple requests concurrently, potentially leading to memory exhaustion.

Mitigation and Solution

The LibHTP team has released a fix for this vulnerability in version 0.5.51. It is highly recommended that users update to this version to avoid exposure. If unable to update immediately, users can mitigate the risk by setting `suricata.yaml app-layer.protocols.http.libhtp.default-config.lzma-enabled` to false. Alternatively, using a Web Application Firewall (WAF) or Intrusion Detection System (IDS) can provide a temporary mitigation against potential exploits.

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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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