The Erlang/OTP ssl application does not detect cycles when reconstructing incomplete peer certificate chains during TLS or DTLS handshakes. Specifically, in ssl_certificate:handle_incomplete_chain/5, the chain is passed to ssl_certificate:build_certificate_chain/5, which calls ssl_certificate:do_certificate_chain/7 without cycle detection or depth limits. If a peer supplies two mutually cross-signed certificates in unordered form, the issuer lookup alternates indefinitely between them, causing infinite recursion that grows the call stack and memory usage without bound. This leads to memory exhaustion and a crash of the BEAM node. The vulnerability affects OTP versions from 23.2 before OTP 29.0.4, 28.5.0.4, and 27.3.4.15, corresponding to ssl versions 10.2 before 11.7.4, 11.6.0.4, and 11.2.12.11.

An unauthenticated remote attacker can exploit this vulnerability by sending a specially crafted certificate chain during a TLS or DTLS handshake, causing uncontrolled recursion that exhausts memory and crashes the Erlang BEAM node. This results in denial of service for both TLS/DTLS clients and servers using the affected ssl application versions. No authentication or completed handshake is required to trigger the issue.

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is available, consider limiting exposure to untrusted TLS/DTLS peers or applying any vendor-recommended temporary mitigations once published.