CVE-2025-4948 in libsoup
Summary
by MITRE • 05/19/2025
A flaw was found in the soup_multipart_new_from_message() function of the libsoup HTTP library, which is commonly used by GNOME and other applications to handle web communications. The issue occurs when the library processes specially crafted multipart messages. Due to improper validation, an internal calculation can go wrong, leading to an integer underflow. This can cause the program to access invalid memory and crash. As a result, any application or server using libsoup could be forced to exit unexpectedly, creating a denial-of-service (DoS) risk.
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Analysis
by VulDB Data Team • 12/10/2025
The vulnerability identified as CVE-2025-4948 resides within the libsoup HTTP library, a critical component that serves as the foundation for web communication in numerous GNOME applications and other software systems. This library implements the soup_multipart_new_from_message() function which processes multipart HTTP messages, a common format for handling file uploads and complex data transfers in web applications. The flaw manifests when the library encounters specially crafted multipart messages that exploit improper validation mechanisms within the internal calculation logic. This particular vulnerability represents a classic example of an integer underflow condition that can be exploited to manipulate memory access patterns and potentially lead to program termination. The issue directly impacts the library's ability to safely process incoming HTTP requests, making it a significant concern for any system relying on libsoup for web communications.
The technical implementation of this vulnerability stems from inadequate input validation within the soup_multipart_new_from_message() function where the library fails to properly check boundary conditions during internal calculations. When processing multipart messages, the function performs arithmetic operations that can result in integer underflow conditions when specific malicious payloads are provided. This occurs because the library does not adequately validate the size parameters or boundary values that determine memory allocation and access patterns. The integer underflow creates a scenario where calculated memory addresses become invalid or point to unexpected locations in memory, leading to memory access violations. This type of vulnerability is classified as CWE-191, which specifically addresses integer underflow conditions that can cause unexpected behavior in program execution. The underlying flaw demonstrates poor defensive programming practices where boundary checks are insufficient to prevent arithmetic overflow or underflow scenarios that can be exploited by attackers.
The operational impact of CVE-2025-4948 extends beyond simple program crashes to create substantial denial-of-service risks for affected systems. Any application or server utilizing the libsoup library becomes vulnerable to this attack vector, including but not limited to web browsers, email clients, and networked applications that depend on HTTP communication. The vulnerability can be exploited remotely by sending specially crafted multipart HTTP messages to a target server, causing the application to terminate unexpectedly and potentially leading to service disruption. This creates a significant risk for web servers, desktop applications, and mobile platforms that rely on GNOME components or other software stacks built upon libsoup. The DoS condition can be particularly problematic in enterprise environments where continuous availability is critical, as even a single exploited instance can cause service interruptions and require system restarts. The vulnerability's exploitation does not require elevated privileges or complex attack chains, making it accessible to a broad range of threat actors and increasing its potential impact across various deployment scenarios.
Mitigation strategies for CVE-2025-4948 should prioritize immediate patching of affected libsoup versions, as this represents the most effective approach to resolving the integer underflow condition. Organizations should implement comprehensive vulnerability management processes to identify all systems utilizing libsoup and ensure timely application of security updates. Network-level mitigations can include implementing content filtering rules to detect and block suspicious multipart message patterns, though this approach may not prevent all exploitation attempts. The vulnerability's nature suggests that defensive programming measures such as implementing proper integer overflow/underflow checks, adding boundary validation for all arithmetic operations, and employing stack canaries could provide additional protection layers. Security monitoring should focus on detecting unusual application termination patterns and unexpected memory access violations that might indicate exploitation attempts. From an ATT&CK perspective, this vulnerability aligns with techniques involving denial-of-service attacks and system manipulation, making it a relevant concern for organizations implementing comprehensive threat hunting and incident response protocols. Additionally, developers should review their code for similar patterns in other libraries or components that might be susceptible to the same class of integer underflow issues, ensuring broader system resilience against similar vulnerabilities.