CVE-2026-109855 undici - Denial of Service

undici 8.11.0 and 8.11.1 contain a denial of service caused by mishandling failed WebSocket handshake over HTTP/2 in the experimental WebSocket client, letting remote unauthenticated servers crash clients, exploit requires opening WebSocket over HTTP/2.

CVSS base score 7.5 /10
High
CISA KEV
Not listed
Public exploit
None known
Authentication
Not required
View the NVD record ↗

Details

Type
Denial of Service
Impact
Denial Of Service
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Published
15 October 2026
Updated
15 October 2026
Weakness
CWE-248

Vendor fix

Upgrade to version 8.11.2 or later.

Patching closes this CVE. It does not tell you which of your systems run the affected version, or what else is exposed alongside them.

References

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