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HIGH

CVE-2026-5680

CVSS v3

7.5

HIGH

EPSS Score

1.1 %

exploit probability, as of 2026-09-25

CISA KEV

No

known exploited

Exploitation

—

SSVC status

Description

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.

Technical details

Published
2026-08-27
Last Modified
2026-08-28

Frequently asked questions

What is CVE-2026-5680?

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.

Is CVE-2026-5680 actively exploited?

Active exploitation of CVE-2026-5680 has not been confirmed. Its EPSS score was 1.1% on 2026-09-25, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2026-5680?

CVE-2026-5680 has a CVSS v3 base score of 7.5 (HIGH severity).

Is CVE-2026-5680 affecting your environment?

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