Undertow: undertow-websockets: undertow: pre-auth dos on websocket endpoint with @serverendpoint class with any @onmessage method
CVSS v3
7.5
HIGH
EPSS Score
—
exploit probability
CISA KEV
No
known exploited
Exploitation
—
SSVC status
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.
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.
Active exploitation of CVE-2026-15565 has not been confirmed. The EPSS score is N/A%, indicating the estimated probability of exploitation in the next 30 days.
CVE-2026-15565 has a CVSS v3 base score of 7.5 (HIGH severity), with vector string 3.1.
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Ranked by exploit probability (EPSS).