CVE-2026-32873 is a vulnerability classified under CWE-825 (Expired Pointer Dereference) affecting the Gleam-based web server 'ewe' in versions from 0.8.0 up to 3.0.4. The root cause lies in the handle_trailers function, which processes HTTP trailer headers in chunked transfer encoding. When the server encounters trailer headers that are either forbidden or undeclared, the function erroneously recurses on the original buffer instead of advancing past the rejected header. Specifically, three code paths (lines 520, 523, and 526) invoke recursion with the same buffer segment, causing the decoder.decode_packet method to repeatedly parse the identical header. This results in an infinite loop without any timeout or escape condition, causing the BEAM virtual machine process to consume 100% CPU indefinitely. The vulnerability can be exploited remotely by unauthenticated clients sending specially crafted chunked HTTP requests that include rejected trailer headers. Because the issue manifests before application-level code execution, no workaround at the application layer is feasible. The impact is a denial-of-service (DoS) condition that can render the affected server unresponsive. The vendor addressed the issue in version 3.0.5 by correcting the buffer handling logic to properly advance past rejected headers, preventing infinite recursion.

The primary impact of CVE-2026-32873 is a denial-of-service condition caused by infinite CPU consumption, which can lead to service outages and degraded availability of applications relying on the 'ewe' web server. Since exploitation requires no authentication and no user interaction, any exposed instance of the affected versions is vulnerable to remote attacks. This can disrupt business operations, degrade user experience, and potentially cause cascading failures in dependent services. Organizations using 'ewe' in production environments may face downtime, loss of customer trust, and increased operational costs due to incident response and recovery efforts. Although no direct confidentiality or integrity impact is reported, the availability impact alone is significant, especially for critical web services. The lack of known exploits in the wild currently reduces immediate risk, but the ease of exploitation and high severity score (CVSS 7.5) indicate a strong potential for future attacks.

The most effective mitigation is to upgrade all affected 'ewe' web server instances to version 3.0.5 or later, where the vulnerability is fixed. Until upgrade is possible, organizations should consider implementing network-level protections such as Web Application Firewalls (WAFs) or Intrusion Prevention Systems (IPS) configured to detect and block suspicious chunked transfer encoding requests with malformed or forbidden trailer headers. Rate limiting and IP reputation filtering can help reduce exposure to automated exploitation attempts. Monitoring BEAM process CPU usage and setting alerts for abnormal spikes can enable early detection of exploitation attempts. Additionally, isolating vulnerable servers behind reverse proxies or load balancers that can sanitize HTTP requests may reduce attack surface. Application developers should avoid relying on application-level workarounds, as the vulnerability triggers before application code execution. Finally, maintain up-to-date threat intelligence feeds to stay informed about emerging exploits targeting this vulnerability.