CVE-2025-32906: A Critical Vulnerability in Libsoup leading to Out-of-Bound Read and Server Crash

An integral part of any productive internet application is the ability to send and receive data over the web securely and accurately. Libraries like libsoup are vital to achieving this functionality. However, even the most advanced and commonly used libraries can contain security flaws, which could have disastrous consequences for web servers and applications alike. One such flaw was discovered in the libsoup library, leading to an out-of-bound read and crashing the HTTP server - CVE-2025-32906.

The Vulnerability

A recent study found a vulnerability in the soup_headers_parse_request() function of libsoup, a widely used library for HTTP parsing and manipulation. This function may be susceptible to an out-of-bound read, which involves reading data that exists outside of the intended boundary. By exploiting this vulnerability, a malicious user can craft an HTTP request that compromises the server's memory and crashes the server. The issue has been allocated the identifier CVE-2025-32906.

Code Snippet

Here's a small code snippet demonstrating the vulnerability in the soup_headers_parse_request() function:

gboolean
soup_headers_parse_request (const char *str, int len,
			    SoupHTTPVersion *ver, guint *status_code,
			    char **reason_phrase)
{
	const char *space1, *space2, *end;

	/* Locate first space and end of line */
	space1 = memchr (str, ' ', len);
	end = memchr (str, '\n', len);

	if (!space1 || space1 >= end)
		return FALSE;

In this code snippet, the soup_headers_parse_request() function is attempting to parse a user-provided input (the str variable) and fill in the information for the SoupHTTPVersion and status code. However, the function does not appropriately validate user input and boundaries before performing the memory search using the memchr() function calls.

Exploit Details

By crafting a specially malformed HTTP request, an attacker can manipulate the server's memory and exploit this out-of-bound read vulnerability. The structure of the HTTP request and the expected response in this case can violate server expectations, which leads to an abrupt crash. The server will be unable to process any more requests after that, essentially taking the server offline.

Original References

Further information and details on the vulnerability can be found in the official sources linked below:
1. CVE-2025-32906 - National Vulnerability Database: https://nvd.nist.gov/vuln/detail/CVE-2025-32906
2. Libsoup Security Advisory: https://libsoup.org/security-advisory-0001.html
3. Libsoup GitHub Repository: https://github.com/libsoup/libsoup

Conclusion

The CVE-2025-32906 vulnerability is a significant security threat to applications and servers that rely on the libsoup library for HTTP parsing and operations. By exploiting this out-of-bound read issue, a malicious user can effectively disrupt the normal functionality of an HTTP server, leading to a denial of service. It is crucial for developers and system administrators to apply necessary security patches, maintain proper input validation, and adopt secure coding practices to mitigate such vulnerabilities.

Timeline

Published on: 04/14/2025 14:15:24 UTC
Last modified on: 05/06/2025 20:15:26 UTC