LibreSSL ocspcheck through version 4.4.0 contains a memory exhaustion flaw that permits an attacker to exhaust system memory by sending an unbounded HTTP response. The vulnerability arises because http_head_read() and http_body_read() continue to stream response headers and body data without imposing size limits, causing the process to consume excessive memory until it crashes, thereby interrupting certificate status checks and potentially killing the ocspcheck service.

OpenBSD LibreSSL versions up to and including 4.4.0 are affected. The memory exhaustion can occur in any deployment that uses ocspcheck to validate certificates.

The CVSS score of 8.2 indicates a high severity. EPSS data is not available, and the vulnerability is not listed in the CISA KEV catalog, suggesting no widespread known exploits yet. Attackers likely need control of an OCSP responder or the ability to intercept plain HTTP AIA OCSP traffic; the attack vector is inferred from the need to send an unbounded HTTP response. Exploitation requires network-level interaction with the ocspcheck process, but the lack of input validation in the HTTP parsing routines makes the flaw readily exploitable when such conditions exist.