CVE-2025-59777 is a NULL pointer dereference vulnerability identified in GNU libmicrohttpd, a lightweight HTTP server library used widely in embedded systems and applications requiring HTTP server capabilities. The vulnerability exists in version 1.0.2 and earlier, where improper handling of certain specially crafted network packets leads to dereferencing a NULL pointer. This results in a denial-of-service (DoS) condition by crashing the affected service, impacting availability. The flaw requires no authentication or user interaction, making it remotely exploitable over the network with low complexity. The vulnerability was addressed in a commit (ff13abc) after the 1.0.2 tag in the libmicrohttpd Git repository, indicating that users must upgrade to versions including this fix or later. Although no known exploits have been reported in the wild, the vulnerability’s characteristics make it a credible threat, especially for services exposed to untrusted networks. The CVSS v3.0 score of 7.5 reflects a high severity due to the network attack vector, low attack complexity, no privileges required, and a direct impact on availability without affecting confidentiality or integrity. This vulnerability primarily threatens systems that embed libmicrohttpd for HTTP server functionality, including IoT devices, network appliances, and some Linux-based services.

For European organizations, the primary impact of CVE-2025-59777 is service disruption due to denial-of-service conditions. This can affect critical infrastructure components, embedded devices, and internal or external-facing HTTP services that rely on vulnerable versions of libmicrohttpd. Disruptions could lead to operational downtime, loss of availability for customers or internal users, and potential cascading effects in environments where these services are integral to business processes or safety systems. Although confidentiality and integrity are not directly impacted, the availability loss can degrade trust and cause financial or reputational damage. Organizations in sectors such as telecommunications, manufacturing (especially with embedded IoT devices), and public services that deploy GNU software stacks are particularly vulnerable. The lack of known exploits currently provides a window for proactive patching before widespread exploitation occurs.

1. Immediately identify all systems and devices running GNU libmicrohttpd version 1.0.2 or earlier within your environment. 2. Upgrade libmicrohttpd to the latest version that includes the fix from commit ff13abc or later. If upgrading is not immediately possible, consider applying any available backported patches or mitigations from trusted sources. 3. Implement network-level protections such as firewall rules or intrusion prevention systems (IPS) to detect and block suspicious or malformed HTTP packets targeting libmicrohttpd services. 4. Monitor logs and network traffic for unusual connection attempts or crashes related to HTTP services using libmicrohttpd. 5. For embedded or IoT devices where patching is challenging, isolate these devices on segmented networks to limit exposure. 6. Engage with vendors or device manufacturers to obtain firmware updates addressing this vulnerability. 7. Incorporate this vulnerability into vulnerability management and incident response processes to ensure timely detection and remediation.