CVE-2024-27316 is a vulnerability classified under CWE-770 (Allocation of Resources Without Limits or Throttling) affecting Apache HTTP Server version 2.4.17. The issue arises during HTTP/2 header processing, where the nghttp2 library buffers incoming headers that exceed predefined limits to generate an HTTP 413 (Payload Too Large) response. However, if a malicious client persistently sends headers beyond these limits without halting, the buffering mechanism leads to uncontrolled memory consumption. This results in memory exhaustion on the server, potentially causing it to crash or become unresponsive, effectively a denial-of-service attack. The vulnerability is remotely exploitable without requiring any authentication or user interaction, increasing its risk profile. The CVSS v3.1 base score is 7.5 (high), reflecting the ease of exploitation and significant impact on availability, while confidentiality and integrity remain unaffected. No patches or fixes are currently linked, and no active exploits have been reported in the wild. The vulnerability highlights a resource management flaw in the HTTP/2 implementation within Apache HTTP Server, emphasizing the need for robust input validation and resource throttling in protocol handling.

For European organizations, this vulnerability poses a significant risk to the availability of web services relying on Apache HTTP Server 2.4.17, particularly those exposing HTTP/2 endpoints. A successful exploitation can lead to server crashes or degraded performance due to memory exhaustion, resulting in denial-of-service conditions. This can disrupt business operations, customer access, and critical online services, especially for sectors such as finance, government, healthcare, and e-commerce that depend heavily on web infrastructure. The lack of impact on confidentiality and integrity reduces risks related to data breaches but availability disruption can still cause reputational damage and financial losses. Organizations with large-scale or high-traffic web servers are particularly vulnerable, as attackers can leverage automated tools to generate excessive HTTP/2 headers at scale. Additionally, the vulnerability could be exploited as part of a broader attack campaign targeting European internet infrastructure, potentially affecting multiple organizations simultaneously.

1. Upgrade Apache HTTP Server to a version where this vulnerability is patched as soon as it becomes available from the Apache Software Foundation. 2. In the interim, implement network-level rate limiting and filtering to detect and block clients sending excessive HTTP/2 headers. 3. Employ Web Application Firewalls (WAFs) capable of inspecting HTTP/2 traffic and enforcing header size limits. 4. Monitor server logs and network traffic for unusual spikes in HTTP/2 header sizes or repeated HTTP 413 responses, which may indicate exploitation attempts. 5. Configure resource limits and timeouts in the HTTP/2 module or underlying nghttp2 library if configurable, to prevent excessive buffering. 6. Conduct regular security assessments and penetration testing focusing on HTTP/2 protocol handling. 7. Educate incident response teams to recognize symptoms of memory exhaustion and DoS conditions related to HTTP/2 traffic.