SB2025120342 - Security restrictions bypass in Fastify-reply-from
Published: December 3, 2025
Security Bulletin ID
SB2025120342
Severity
Medium
Patch available
YES
Number of vulnerabilities
1
Exploitation vector
Remote access
Highest impact
Data manipulation
Breakdown by Severity
- Low
- Medium
- High
- Critical
Description
This security bulletin contains information about 1 security vulnerability.
1) Unintended proxy or intermediary (CVE-ID: CVE-2025-66415)
The vulnerability allows a remote attacker to bypass implemented security restrictions.
The vulnerability exists due to improper input validation when handling the ".." characters in URLs. A remote attacker can use a specially crafted URL to access routes that are not allowed, even though the reply.from is defined for specific routes in @fastify/reply-from.
Remediation
Install update from vendor's website.