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CVE intelligence

CVE-2026-91768

Vulnerability intelligence

Published Sep 25, 2026Sources checked Sep 29, 2026
6.5MEDIUMCVSS out of 10
What this means

Review the available evidence

CVE-2026-91768 and is rated Medium severity with a CVSS score of 6.5. It is not in the current CISA KEV record we collected. That does not prove exploitation has not occurred.

What to do next

Remediation and response

CISA KEVNot listedBased on the latest collected catalog
EPSS0.6%Estimated 30-day exploitation probability
Ransomware useNot markedCISA KEV ransomware field
Threat actors0Source-linked actor relationships
Overview

What is CVE-2026-91768?

The IPv6 branch of the FastCGI client access check compares only the first 12 bytes of a 16-byte IPv6 address, so listen.allowed_clients matches on a /96 prefix instead of the exact address. An attacker who can source an address sharing the first 96 bits with an allowed one passes the check and reaches the FastCGI endpoint.