CVE-2025-59530: Quic-Go

High severity, CVSS 7.5. EPSS: 0.5% chance of exploitation in the next 30 days.

quic-go is an implementation of the QUIC protocol in Go. In versions prior to 0.49.0, 0.54.1, and 0.55.0, a misbehaving or malicious server can cause a denial-of-service (DoS) attack on the quic-go client by triggering an assertion failure, leading to a process crash. This requires no authentication and can be exploited during the handshake phase. This was observed in the wild with certain server implementations. quic-go needs to be able to handle misbehaving server implementations, including those that prematurely send a HANDSHAKE_DONE frame. Versions 0.49.0, 0.54.1, and 0.55.0 discard Initial keys when receiving a HANDSHAKE_DONE frame, thereby correctly handling premature HANDSHAKE_DONE frames.

Affected products

• Quic-Go Quic-Go: before 0.49.1 (fixed in 0.49.1); from 0.5.0, before 0.54.1 (fixed in 0.54.1)

Published 2025-10-10. Last modified 2026-06-17.