Description

An issue in ACME mini_httpd 1.30 and prior allows a remote attacker to cause a denial of service via the HTTP request header parser in the handle_request() function

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "7.5",
  "pubDate": "2026-08-17T20:16:45.347Z",
  "pubdate": "2026-08-17T20:16:45.347Z",
  "executiveSummary": "An availability vulnerability exists within ACME mini_httpd versions 1.30 and prior, specifically residing within the HTTP request header parser of the handle_request() function. This security flaw enables a remote, unauthenticated attacker to induce a denial of service condition against the targeted web server instance. The primary impact of this vulnerability is the disruption of service availability, rendering the affected web application or service inaccessible to legitimate users. The risk implication is significant for systems exposed to untrusted networks, as successful exploitation disrupts core business operations without requiring elevated privileges or prior access to the underlying system. Exploitation requires network connectivity to the vulnerable mini_httpd service and the transmission of a maliciously crafted HTTP request designed to trigger parsing anomalies or resource exhaustion within the affected function. Because mini_httpd is often deployed in resource-constrained environments or embedded systems, such denial of service conditions can severely impact device stability and operational continuity.",
  "technicalDetails": "The vulnerability is localized to the HTTP request header parser implemented within the handle_request() function of ACME mini_httpd version 1.30 and prior. The root cause stems from improper handling or parsing logic when processing incoming HTTP request headers, leading to anomalous execution states, infinite loops, memory corruption, or excessive resource consumption. Network exposure is direct, as the vulnerable function processes raw TCP streams containing HTTP requests received from remote clients over the network interface. Authentication and privilege requirements are nonexistent, allowing any unauthenticated remote attacker to initiate the attack vector by establishing a TCP connection to the listening web server port. The attack flow initiates when the remote attacker crafts a specialized HTTP request containing malformed, oversized, or unexpectedly structured header fields. Upon transmission, the mini_httpd daemon accepts the connection and passes the raw byte stream to the handle_request() function for parsing. As the vulnerable parsing logic attempts to interpret the malicious header structure, it encounters unexpected syntax or boundary conditions that it fails to handle gracefully. This failure results in abnormal program termination, a segmentation fault, or an infinite processing loop that consumes 100 percent of available CPU resources. Consequently, the single-threaded or event-handling architecture of mini_httpd becomes unresponsive, halting the processing of subsequent legitimate HTTP requests and achieving a complete denial of service. Post-exploitation impact is limited to service unavailability and potential daemon crashes; however, depending on the exact nature of the parsing flaw, further impacts such as arbitrary code execution cannot be definitively ruled out without vendor patches or source code auditing."
}