What is CVE-2026-18174?

CVE-2026-18174 is a medium-severity vulnerability in @Fastify/forwarded, classified under Improper Input Validation. CVSS score: 5.3/10. Published 2026-07-29.

How severe is CVE-2026-18174?

Medium severity. CVSS v3 base score is 5.3 out of 10.

Improper input validation in @Fastify/forwarded

CVE-2026-18174

@fastify/forwarded resolves client addresses from the X-Forwarded-For header. In versions before 3.0.2, when the header contains two or more comma separated entries, the parser trims only space characters and does not strip horizontal tabs…

Vulnerability class: Drupalgeddon 2 (CVE-2018-7600)

CVSS v3 metric

CVSS v3 base score 5.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N.

Affected products

@Fastify/forwarded — versions 0, 3.0.2

Weakness classification (CWE)

CWE-20 — Improper Input Validation
CWE-184 — Incomplete List of Disallowed Inputs

References

ce714d77-add3-4f53-aff5-83d477b104bb
ce714d77-add3-4f53-aff5-83d477b104bb

Frequently asked questions

What is CVE-2026-18174?: CVE-2026-18174 is a medium-severity vulnerability in @Fastify/forwarded, classified under Improper Input Validation. CVSS score: 5.3/10. Published 2026-07-29.
How severe is CVE-2026-18174?: Medium severity. CVSS v3 base score is 5.3 out of 10.