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CVE-2026-15565highCWE-120

Undertow: undertow-websockets: undertow: pre-auth dos on websocket endpoint with @serverendpoint class with any @onmessage method

21Vexday Risk Score

No sign of exploitation. No public exploitation artifact known so far.

ssvc Trackcvss 7.5epss 0.5%
exploitation probability
0.5%top 57% of all CVEs
observed exploitation
nono source reports it
A flaw was found in Undertow. A remote attacker can cause Out of Memory on websockets endpoint without authentication on any @ServerEndpoint class that has any @OnMessage method. This allows an attacker to cause Denial of Service attack without authentication and using only a standard WebSocket handshake.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H