Node crash via unbounded WebSocket resource allocation
Published Sep 23, 2026 · Updated Sep 23, 2026
Resource exhaustion in Klever klever-go before 1.7.20 allows remote attackers to crash a node through the open /subscribe WebSocket. The handler accepts unlimited message sizes, connections, and address subscriptions, retaining attacker-controlled data, goroutines, channels, and descriptors in the node process. The attack requires access to the REST listener; permissive origin handling also exposes a localhost-bound node when an operator visits a malicious page.
Summary
What happened
Resource exhaustion in Klever klever-go before 1.7.20 allows remote attackers to crash a node through the open /subscribe WebSocket. The handler accepts unlimited message sizes, connections, and address subscriptions, retaining attacker-controlled data, goroutines, channels, and descriptors in the node process. The attack requires access to the REST listener; permissive origin handling also exposes a localhost-bound node when an operator visits a malicious page.
The record
- CVE
- CVE-2026-86065
- Published
- Sep 23, 2026
- Updated
- Sep 23, 2026
- Vendor
- Klever
- Product
- klever-go
- Classifications
- CWE-770, T1499.004
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Sep 23, 2026CVE publishedPublication date reported by the CVE source.
- Sep 23, 2026Record 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.
- Affected versionversion=< 1.7.20
What conditions does exploitation require?
What is affected?
Published CVSS scores
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.
Activity data is delayed. The latest report is Sep 28, 2026.
Weakness, pattern, technique
Public exploit references
- End-to-end /subscribe WebSocket exhaustion proof of conceptfunctional · demonstrated
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Technologies
Your stack
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Your stack
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