What’s Vulnerable › Vulnerabilities

CVE-2025-66415: fastify-reply-from bypass of reply forwarding

• Severity: medium (CVSS 5.4 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.2% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2025-12-01 · updated 2026-10-18
• Weakness: CWE-441

Description

fastify-reply-from is a Fastify plugin to forward the current HTTP request to another server. Prior to 12.5.0, by crafting a malicious URL, an attacker could access routes that are not allowed, even though the reply.from is defined for specific routes in @fastify/reply-from. This vulnerability is fixed in 12.5.0.

Affected products

• fastify-reply-from: through 12.4.0

References

• https://github.com/fastify/fastify-reply-from/commit/4d9795cd5b57a36756d37b7f036eae369f69fa66
• https://github.com/fastify/fastify-reply-from/security/advisories/GHSA-2q7r-29rg-6m5h

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