# CVE-2025-66482: misskey-js — Fix Available

📦 npm

Not in CISA KEV

# CVE-2025-66482 — misskey-js

[Fix: misskey-dev/misskey@5512898](https://github.com/misskey-dev/misskey/commit/5512898463fa8487b9e6488912f35102b91f25f7)

CVE-2025-66482 is a CWE-307 vulnerability in misskey-js. A fix is available for misskey-js — see the affected versions and patch details below.

Misskey has a login rate limit bypass via spoofed X-Forwarded-For header

Also known as[GHSA-wwrj-3hvj-prpm](/vulnerability/GHSA-wwrj-3hvj-prpm)

Published

Dec 15, 2025

Updated

Oct 28, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Oct 24, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

## Exploitation Status

### Proof-of-concept exploit code exists

-   CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
-   CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.

Exploitation and automatability from CISA’s SSVC triage for CVE-2025-66482.

## EPSS Exploitation Probability

[via FIRST.org ↗](https://www.first.org/epss/)

0.3%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs26th percentile — riskier than 26% of all scored CVEsHighest risk

0.00%0.28%0.56%0.84%0.1%0.3%Apr 26Aug 26Oct 26

Probability of exploitation in the next 30 days, from [FIRST.org EPSS](https://www.first.org/epss/).

## Real-World Exposure

1 pkg affected

How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.

1other npm packages depend on this — each one inherits the vulnerability until it's patched upstream

`misskey-js`npm

1Kdownloads / week

## Description

#### Summary

When using an untrusted reverse proxy or not using a reverse proxy at all, attackers can bypass IP rate limiting by adding a forged X-Forwarded-For header. Starting with version 2025.9.1, an option (`trustProxy`) has been added in config file to prevent this from happening. However, it is initialized with an insecure default value before version 2025.12.0, making it still vulnerable if the configuration is not set correctly.

#### Workaround

If you are running Misskey with a trusted reverse proxy, you should _not_ be affected by this vulnerability.

-   There is no workaround for the Misskey itself. Please update Misskey to the latest version or set up a trusted reverse proxy.
-   From v2025.9.1 to v2025.11.1, workaround is available. Set `trustProxy: false` in config file.
-   This is patched in v2025.12.0 by flipping default value of `trustProxy` to `false`. If you are using trusted reverse proxy and not remember you manually overrided this value, please take time to check your config for optimal behavior.

#### Details

[Fastify recommend not trusting X-Forwarded-For IPs](https://fastify.dev/docs/latest/Reference/Server/#trustproxy) Due to misconfiguration in [https://github.com/misskey-dev/misskey/blob/develop/packages/backend/src/server/api/SigninApiService.ts#L94](https://github.com/misskey-dev/misskey/blob/develop/packages/backend/src/server/api/SigninApiService.ts#L94) attacks can spoof their IPs.

#### PoC

```
POST /api/signin-flow HTTP/1.1
Host: misskey.localhost:3123
Content-Length: 45
Content-Type: application/json
Connection: keep-alive
X-Forwarded-For: 127.1.1.31, 1.1.1.12

{"username":"admin",
	"password":"password"}
```

![image](https://github.com/user-attachments/assets/ce9f77e2-b339-4081-86a6-d44ed42e9ca5)

#### Impact

An attacker can brute force accounts bypassing rate limiting protection.

## Affected Packages

1 total 1 fixed

Ecosystem

Package

Vulnerable range

Fix

📦npm

`misskey-js` 

≥ 2025.9.1&&< 2025.12.0-alpha.2

2025.12.0-alpha.2`npm install misskey-js@2025.12.0-alpha.2`

## Affected Products

1 product · 37 configurations

Application

`misskey`misskey

≥ 13.1.0 && < 2025.12.0

1 version

13.0.0

## Detection & mitigation playbook

Open-source dependency

1.  ### Detect
    
    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for misskey-js, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
    
2.  ### Fix
    
    Update misskey-js to 2025.12.0-alpha.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2025-66482 is resolved across your whole dependency graph.
    
3.  ### Workarounds
    
    If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
    

## Frequently Asked Questions

\### Summary When using an untrusted reverse proxy or not using a reverse proxy at all, attackers can bypass IP rate limiting by adding a forged X-Forwarded-For header. Starting with version 2025.9.1, an option (\`trustProxy\`) has been added in config file to prevent this from happening. However, it is initialized with an insecure default value before version 2025.12.0, making it still vulnerable if the configuration is not set correctly. ### Workaround If you are running Misskey with a trusted reverse proxy, you should \*not\* be affected by this vulnerability. - There is no workaround for the

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