CVE-2026-92395 @fastify/proxy-addr - Broken Access Control

@fastify/proxy-addr 3.0.0 through 5.1.0 contains a broken access control vulnerability caused by improper handling of IPv4-mapped IPv6 trust subnets, letting unauthenticated clients bypass IP-based restrictions by controlling X-Forwarded-For header, exploit requires crafted X-Forwarded-For header.

CVSS base score 9.1 /10
Critical
CISA KEV
Not listed
Public exploit
None known
Authentication
Not required
EPSS
0.33% chance of exploitation in 30 days
View the NVD record ↗

Details

Type
Broken Access Control
Impact
Broken Access Control
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
Published
16 September 2026
Updated
15 October 2026
Weakness
CWE-290

Vendor fix

Upgrade to version 5.1.1 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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