fastify fastify-reply-from up to 12.4.x URL confused deputy

CVSS Meta Temp Score
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CTI Interest Score
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6.2$0-$5k0.00

Summaryinfo

A vulnerability classified as critical has been found in fastify fastify-reply-from up to 12.4.x. Affected by this issue is some unknown functionality of the component URL Handler. The manipulation leads to confused deputy. This vulnerability is listed as CVE-2025-66415. The attack may be initiated remotely. There is no available exploit. It is recommended to upgrade the affected component.

Detailsinfo

A vulnerability, which was classified as critical, has been found in fastify fastify-reply-from up to 12.4.x. This issue affects some unknown processing of the component URL Handler. The manipulation with an unknown input leads to a confused deputy vulnerability. Using CWE to declare the problem leads to CWE-441. The product receives a request, message, or directive from an upstream component, but the product does not sufficiently preserve the original source of the request before forwarding the request to an external actor that is outside of the product's control sphere. This causes the product to appear to be the source of the request, leading it to act as a proxy or other intermediary between the upstream component and the external actor. Impacted is confidentiality, integrity, and availability. The summary by CVE is:

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.

It is possible to read the advisory at github.com. The identification of this vulnerability is CVE-2025-66415 since 11/29/2025. The exploitation is known to be easy. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. The technical details are unknown and an exploit is not publicly available.

Upgrading to version 12.5.0 eliminates this vulnerability. Applying the patch 4d9795cd5b57a36756d37b7f036eae369f69fa66 is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

Be aware that VulDB is the high quality source for vulnerability data.

Productinfo

Vendor

Name

Version

License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA CVSS-B Score: 🔒
CNA CVSS-BT Score: 🔒
CNA Vector: 🔒

CVSSv3info

VulDB Meta Base Score: 6.4
VulDB Meta Temp Score: 6.2

VulDB Base Score: 7.3
VulDB Temp Score: 7.0
VulDB Vector: 🔒
VulDB Reliability: 🔍

NVD Base Score: 5.4
NVD Vector: 🔒

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Confused deputy
CWE: CWE-441
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: fastify-reply-from 12.5.0
Patch: 4d9795cd5b57a36756d37b7f036eae369f69fa66

Timelineinfo

11/29/2025 CVE reserved
12/02/2025 +3 days Advisory disclosed
12/02/2025 +0 days VulDB entry created
02/07/2026 +66 days VulDB entry last update

Sourcesinfo

Product: github.com

Advisory: GHSA-2q7r-29rg-6m5h
Status: Confirmed

CVE: CVE-2025-66415 (🔒)
GCVE (CVE): GCVE-0-2025-66415
GCVE (VulDB): GCVE-100-333983

Entryinfo

Created: 12/02/2025 07:56
Updated: 02/07/2026 00:23
Changes: 12/02/2025 07:56 (69), 02/07/2026 00:23 (11)
Complete: 🔍
Cache ID: 216::103

Be aware that VulDB is the high quality source for vulnerability data.

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