CVE-2025-59530Known exploitationNetwork attack vector

Client process crash via premature HANDSHAKE_DONE frame

Published Oct 10, 2025 · Updated Oct 10, 2025

Reachable assertion in quic-go before 0.49.1 and 0.50.0 through 0.54.0 allows remote attackers to crash client processes during QUIC handshakes. The client accepts a premature HANDSHAKE_DONE frame, discards Handshake keys before Initial keys, then reaches an assertion that no undecryptable packets remain queued after handshake completion. A malicious or noncompliant server needs only to send the frame during an incomplete handshake; the bounded consequence is termination of the process embedding the client library.

CVSS severity7.5
High
EPSS probability0.46%
Next 30 days · Sep 16, 2026
Known exploitationReported
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Reachable assertion in quic-go before 0.49.1 and 0.50.0 through 0.54.0 allows remote attackers to crash client processes during QUIC handshakes. The client accepts a premature HANDSHAKE_DONE frame, discards Handshake keys before Initial keys, then reaches an assertion that no undecryptable packets remain queued after handshake completion. A malicious or noncompliant server needs only to send the frame during an incomplete handshake; the bounded consequence is termination of the process embedding the client library.

The record

CVE
CVE-2025-59530
Published
Oct 10, 2025
Updated
Oct 10, 2025
Vendor
quic-go
Product
quic-go
Classifications
CWE-755, CWE-617, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Oct 10, 2025CVE publishedPublication date reported by the CVE source.
  2. Oct 10, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 0.49.1
  2. Affected versionversion=>= 0.5.0, < 0.54.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

quic-go · quic-goversion=< 0.49.1; version=>= 0.5.0, < 0.54.1

Published CVSS scores

7.5GitHubCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationReported
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-755Improper Handling of Exceptional Conditions
CWE-617Reachable Assertion
T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Reported exploitation

Technologies

Your stack

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Your stack

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