CVE-2025-59530

CVE-2025-59530 is a high-severity vulnerability with a CVSS 3.x base score of 7.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-617.

Key facts

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.

Frequently asked questions

What is CVE-2025-59530?
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.
How severe is CVE-2025-59530?
CVE-2025-59530 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2025-59530 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (35th percentile), an estimate of the probability of exploitation in the next 30 days.
How do I fix CVE-2025-59530?
Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2025-59530 have an EU (EUVD) identifier?
Yes. CVE-2025-59530 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-33746.
When was CVE-2025-59530 published?
CVE-2025-59530 was published on 2025-10-10 and last updated on 2026-06-17.

References

Other CWE-617 (Reachable Assertion) vulnerabilities

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