A vulnerability in the CivetWeb library's function mg_handle_form_request allows remote attackers to trigger a denial of service (DoS) condition. By sending a specially crafted HTTP POST request containing a null byte in the payload, the server enters an infinite loop during form data parsing. Multiple malicious requests will result in complete CPU exhaustion and render the service unresponsive to further requests. This issue was fixed in commit 782e189. This issue affects only the library, standalone executable pre-built by vendor is not affected.
Ubuntu USN-8749-1 patches CivetWeb URI and HTTP request parsing flaws enabling remote DoS or possible code execution.
Ubuntu Security Notice USN-8749-1 addresses two CivetWeb vulnerabilities. CVE-2025-55763 involves incorrect URI parsing that could allow a remote attacker to cause denial of service or execute arbitrary code, affecting Ubuntu 22.04 LTS and 24.04 LTS. CVE-2025-9648 involves incorrect HTTP request parsing enabling remote denial of service.