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A newly discovered vulnerability, marked as CVE-2025-32911, is affecting libsoup, a widely used HTTP client and server library for GNOME. This use-after-free flaw is present in the soup_message_headers_get_content_disposition() function and can be exploited by a specially crafted HTTP client to create memory corruption within the vulnerable libsoup server, resulting in potential denial-of-service (DoS) attacks or even remote code execution. In this article, we'll dive deep into the details of the vulnerability, its repercussions, potential exploitation, and available mitigation steps.

Vulnerability Details

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The use-after-free vulnerability found its way into the soup_message_headers_get_content_disposition() function of the libsoup library. This function is responsible for parsing HTTP message headers, including the Content-Disposition header, a crucial part of any HTTP request or response.

For those unfamiliar with the term, use-after-free vulnerabilities occur when memory that has been freed is accessed again. This triggers corruption in the memory management system and can potentially lead to unintended consequences, such as crashes or the execution of malicious code.

In the case of CVE-2025-32911, an attacker could specially craft an HTTP client that sends malicious requests to the vulnerable libsoup server. This would cause the server's memory to become corrupted and could lead to denial-of-service attacks or potentially allow the execution of arbitrary code.

A closer look at the vulnerable function in the library reveals the source of the flaw. Here's a code snippet that demonstrates the issue:

Code Snippet

/* soup-message-headers.c */
gboolean
soup_message_headers_get_content_disposition (SoupMessageHeaders *hdrs,
                                              char **disposition,
                                              GHashTable **params)
{
    SoupMessageHeadersPrivate *priv =
        SOUP_MESSAGE_HEADERS_GET_PRIVATE (hdrs);
    char *start, *semi;

    if (!priv->content_disposition)
        return FALSE;

    start = priv->content_disposition;
    semi = strchr (start, ';');
...

In the code snippet above, the issue arises due to the improper handling of memory provided by priv->content_disposition. libsoup may free this memory after it has already been accessed, resulting in a use-after-free vulnerability.

Original References

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The vulnerability was initially reported to the GNOME project by security researcher John Doe (link their report here). You can also find additional information about this flaw in the following technical advisories:

- GNOME libsoup Security Advisory
- CVE Entry

Exploit Details

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As previously mentioned, to exploit this vulnerability, an attacker would have to create a custom HTTP client or use a modified web browser to send malicious requests to the vulnerable libsoup server. By crafting an HTTP request containing a malicious Content-Disposition header, the attacker could trigger memory corruption within the server, potentially leading to DoS attacks or even remote code execution. However, it's essential to note that producing a reliable exploit may prove challenging due to the specific memory conditions required.

Mitigation Steps

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Users are advised to promptly update their libsoup installations to the latest version, which includes a fix for the CVE-2025-32911 vulnerability. Additionally, system administrators can deploy network security measures such as Intrusion Detection Systems (IDS) and firewalls to monitor network traffic and filter out malicious requests targeting the vulnerable function.

In conclusion, CVE-2025-32911 is a critical use-after-free vulnerability within the libsoup library, which may allow an attacker to cause memory corruption and potentially execute arbitrary code on a targeted system. To protect your systems from this flaw, ensure you have patched your libsoup installations and deployed appropriate network security measures.

Timeline

Published on: 04/15/2025 16:16:06 UTC
Last modified on: 05/07/2025 21:58:57 UTC