CVE-2025-59777 identifies a NULL pointer dereference vulnerability in the GNU Project's libmicrohttpd library, specifically affecting versions 1.0.2 and earlier. Libmicrohttpd is a lightweight HTTP server library commonly used in embedded systems and applications requiring HTTP server capabilities. The vulnerability arises when the library processes a specially crafted network packet that causes it to dereference a NULL pointer, leading to a crash of the HTTP server component. This results in a denial-of-service (DoS) condition, disrupting availability of services relying on libmicrohttpd. The flaw does not impact confidentiality or integrity but solely affects availability. Exploitation requires no authentication or user interaction and can be performed remotely, increasing the risk profile. The issue was addressed in a commit (ff13abc) on the master branch after the 1.0.2 release, indicating that users of the affected versions should upgrade to a patched version. No public exploits have been reported yet, but the vulnerability's characteristics make it a plausible target for attackers aiming to disrupt services. The CVSS v3.0 score of 7.5 reflects a high severity due to network attack vector, low complexity, no privileges required, and a high impact on availability.

For European organizations, the primary impact of CVE-2025-59777 is service disruption due to denial-of-service conditions in applications or devices using vulnerable versions of libmicrohttpd. This can affect embedded devices, network appliances, or software components that rely on libmicrohttpd for HTTP server functionality. Critical infrastructure sectors such as telecommunications, energy, and manufacturing that deploy embedded systems with this library may experience outages or degraded service availability. The lack of confidentiality or integrity impact limits data breach risks, but operational continuity could be compromised. Disruption of services could lead to financial losses, reputational damage, and potential regulatory scrutiny under frameworks like GDPR if service availability is critical to compliance. The remote and unauthenticated nature of the exploit increases the risk of widespread attacks, especially if automated scanning tools identify vulnerable systems. Organizations with large deployments of GNU software or embedded Linux-based devices are particularly vulnerable.

European organizations should immediately inventory all systems and applications that use GNU libmicrohttpd, focusing on versions 1.0.2 and earlier. They should upgrade to the latest patched version of libmicrohttpd that includes the fix from commit ff13abc or later. Where upgrading is not immediately feasible, organizations should implement network-level protections such as firewall rules or intrusion prevention systems (IPS) to detect and block malformed packets targeting libmicrohttpd. Monitoring network traffic for unusual HTTP requests or crashes in services using libmicrohttpd can provide early detection of exploitation attempts. Additionally, applying strict input validation and rate limiting on HTTP endpoints can reduce the risk of triggering the vulnerability. For embedded devices, coordinate with vendors to obtain firmware updates or patches. Finally, incorporate this vulnerability into incident response plans to quickly address any DoS incidents caused by exploitation.