Executive brief
OpenSSL's QUIC implementation can be forced to accumulate memory indefinitely when processing traffic from a malicious peer. An attacker who can establish a QUIC connection can trigger a denial of service by causing the server to retain excessive metadata in memory, exhausting system resources and disrupting service availability for legitimate users.
Technical details
This is an algorithmic resource allocation vulnerability (CWE-770) in OpenSSL's QUIC stack. When the stack sends ACK-only packets, it retains the associated metadata in packet history structures regardless of whether the peer acknowledges them. An attacker can exploit this by completing a QUIC handshake, then sending repeated PING frames to force ACK-only responses from the target, while withholding acknowledgments of ack-eliciting packets. This causes unbounded memory growth on the connection. The vulnerability requires network-level access and successful QUIC handshake completion. The fix involves accounting for ACK-only transmissions in packet history watermarks without storing the packet metadata itself.
Affected products
- OpenSSL OpenSSL <UNKNOWN>
Timeline
- 2026-08-25: disclosed