Application denial of service via exponential buffer growth
Published Aug 27, 2026 · Updated Aug 27, 2026
Resource-consumption DoS in Undertow allows remote attackers to interrupt affected applications via compressed WebSocket messages. PerMessageDeflateFunction.largerBuffer() repeatedly doubles its buffer while expanding attacker-controlled permessage-deflate data without an effective size limit. Exploitation requires a reachable WebSocket endpoint that negotiates permessage-deflate; successful requests exhaust memory and interrupt the affected application.
Summary
What happened
Resource-consumption DoS in Undertow allows remote attackers to interrupt affected applications via compressed WebSocket messages. PerMessageDeflateFunction.largerBuffer() repeatedly doubles its buffer while expanding attacker-controlled permessage-deflate data without an effective size limit. Exploitation requires a reachable WebSocket endpoint that negotiates permessage-deflate; successful requests exhaust memory and interrupt the affected application.
The record
- CVE
- CVE-2026-5680
- Published
- Aug 27, 2026
- Updated
- Aug 27, 2026
- Vendor
- 389 Directory Server
- Product
- Red Hat JBoss Enterprise Application Platform Expansion Pack
- Classifications
- CWE-770, T1499.004
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Aug 27, 2026CVE publishedPublication date reported by the CVE source.
- Aug 27, 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?
Affected versions are unavailable in this record. Check the vendor advisory for version and patch details.
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
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Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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Your stack
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