CVE-2026-5680: Undertow-core: undertow: denial of service via websocket permessage-deflate processing
A flaw was found in Undertow. A remote attacker could exploit this vulnerability by sending specially crafted WebSocket messages with permessage-deflate negotiated. This could lead to excessive memory consumption due to the PerMessageDeflateFunction.largerBuffer() method using exponential doubling, resulting in a Denial of Service (DoS) for the affected application.
Affected Software
Event History
Frequently Asked Questions
Which deployments are exposed to this denial-of-service condition?
Affected Undertow applications are exposed when they accept WebSocket connections that negotiate the permessage-deflate extension. The issue can cause excessive memory consumption in the affected application.
What does an attacker need to exploit the issue?
An attacker can exploit the flaw remotely without privileges or user interaction by sending specially crafted WebSocket messages after permessage-deflate has been negotiated.
What is the impact of successful exploitation?
Successful exploitation can consume excessive memory and cause a denial of service for the affected application. The provided information does not indicate confidentiality or integrity impact.