CVE-2026-91768NVD

Vulnerability Summary

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.

Severity Level

MEDIUM(6.5)

Published Date

Sep 25, 2026

Last Modified

Sep 25, 2026

Exploitation Status

No confirmed exploitation yet

CVE Record Status

Published

EPSS Score (30-Day)

Data Pending

Root Weakness (CWE)

CWE-1023: Unknown/Unlisted Weakness ↗

Refer to the official MITRE database for detailed architectural specifications regarding this weakness.

CVSS v3.1 Base Metrics — Score 6.5 (MEDIUM)

Attack VectorAdjacent

Attack ComplexityLow

Privileges RequiredNone

User InteractionNone

ScopeUnchanged

ConfidentialityHigh

IntegrityNone

AvailabilityNone

Affected & Patched Versions

Affected Versions

Not provided by NVD for this CVE.

Patched Versions

Not provided by NVD for this CVE.

🎁7-Day Free Trial — Try Pro or Team, no card required.

📧Email Delivery — Threat intel straight to your inbox.

♾️Unlimited Vendors — Track your entire stack.

🚨All New CVEs — Be the first to know.

📈EPSS Spike Alerts — Catch rising risk before it peaks.

🎯Custom EPSS/CVSS — Filter noise, focus on risk.

🛡️Exploit Intel — A 2nd confirmed-exploit signal beyond KEV.

🐙GitHub Issues — Auto-tracked, no duplicates.

📬Weekly Digest — One clean summary, not inbox spam.

🏷️Watchlist Groups — Tag alerts by team (Infra/AppSec/SOC).

💬Webhooks — Slack & Teams integration.

🔀Smart Routing — Critical alerts to one channel, rest to another.

🚫Ad-Free — Uninterrupted experience.