CVE-2026-33307

CVE-2026-33307 describes a high-severity stack buffer overflow (CWE-121) in mod_gnutls, a TLS module for Apache HTTPD, affecting versions prior to 0.12.3 and 0.13.0 when client certificate verification is enabled. An unauthenticated attacker can exploit this vulnerability over the network by presenting an excessively long client certificate chain. This typically leads to a denial of service through a server segfault, though theoretical stack corruption is also possible, without writing attacker-controlled data to the buffer. There is currently no evidence of active exploitation, public exploit code, or significant community discussion surrounding this vulnerability.