CVE-2025-23020Network attack vector

Server stall via predictable connection-ID hashing

Published Feb 20, 2025 · Updated Feb 20, 2025

Hash-based denial of service in Kwik before 0.10.1 allows remote attackers to stall QUIC servers with colliding connection IDs. ConnectionSource uses predictable Arrays.hashCode results as keys in the server connection registry, forcing colliding entries into costly hash-table operations. Unauthenticated clients can choose SCIDs during connection initiation, causing excessive CPU consumption without reading or altering data.

CVSS severity5.3
Medium
EPSS probability0.58%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Hash-based denial of service in Kwik before 0.10.1 allows remote attackers to stall QUIC servers with colliding connection IDs. ConnectionSource uses predictable Arrays.hashCode results as keys in the server connection registry, forcing colliding entries into costly hash-table operations. Unauthenticated clients can choose SCIDs during connection initiation, causing excessive CPU consumption without reading or altering data.

The record

CVE
CVE-2025-23020
Published
Feb 20, 2025
Updated
Feb 20, 2025
Vendor
Peter Doornbosch
Product
Kwik
Classifications
CWE-407, T1499.003
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 20, 2025CVE publishedPublication date reported by the CVE source.
  2. Feb 20, 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 <0.10.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Peter Doornbosch · Kwikversion=0 <0.10.1

Published CVSS scores

5.3MITRECVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

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.

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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 exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-407Inefficient Algorithmic Complexity
T1499.003Application Exhaustion Flood

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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