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CVE-2025-59530: quic-go has Client Crash Due to Premature HANDSHAKE_DONE Frame

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.5% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2025-10-10 · updated 2026-10-19
• Weakness: CWE-617

Description

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: before 0.49.1; from 0.5.0, < 0.54.1

References

• https://github.com/quic-go/quic-go/blob/v0.55.0/connection.go#L2682-L2685
• https://github.com/quic-go/quic-go/pull/5354
• https://github.com/quic-go/quic-go/security/advisories/GHSA-47m2-4cr7-mhcw

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