fastify-reply-from bypass of reply forwarding
Priority LOW 30CWE-441Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Attack requirements
- None
- Impact type
- —
- Confidentiality · integrity · availability
- Low · Low · None
- Fix status
- Partial Red Hat: 2 without a fix
Attack profile from CVSS 4.0 · CNA. Fix status from CNA, GitHub and Red Hat.
Summary
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.
Why it matters now
Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00191 8th percentileScored 2026-11-07
Fix Partial fastify-reply-from (fastify): 12.5.0@fastify/reply-from (npm): 12.5.0Red Hat: 2 without a fix
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| fastify | fastify-reply-from | before 12.5.0 | 12.5.0 | Patch available | CNA |
| — | @fastify/reply-from (npm) | before 12.5.0 | 12.5.0 | Patch available | GHSA-2q7r-29rg-6m5h |
- fastify-reply-from Vendorfastify Affected before 12.5.0 Fixed in 12.5.0 Patch available CNA
- @fastify/reply-from (npm) Vendor— Affected before 12.5.0 Fixed in 12.5.0 Patch available GHSA-2q7r-29rg-6m5h
Remediation
- Fix · CNA fastify-reply-from (fastify) Fixed in 12.5.0
- Fix · GHSA-2q7r-29rg-6m5h @fastify/reply-from (npm) Fixed in 12.5.0 Advisory →
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat OpenShift AI (RHOAI) | Affected | No fix yet: Fix deferred |
| Red Hat OpenShift Dev Spaces | Affected | No fix yet: Fix deferred |
Timeline
- 2026-10-02 Threatist record created from CVE-2025-66415
- 2026-10-03 Alias added: GHSA-2q7r-29rg-6m5h
References
More fastify Reply-from vulnerabilities
- TI-2026-26177 @fastify/reply-from vulnerable to connection header abuse enabling stripping of proxy-added headers CVSS 4.0CRITICAL 9.0
- TI-2023-28347 @fastify-reply-from JSON Content-Type parsing confusion CVSS 3.1HIGH 7.5
Sources
- CVE-2025-66415 · CVE Program
- CVE-2025-66415 · NVD
- FIRST EPSS
- GHSA-2q7r-29rg-6m5h · GitHub Advisory Database · CC BY 4.0
- CVE-2025-66415 · Red Hat security data · CC BY 4.0
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