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GHSA-wwrj-3hvj-prpm
No affected components available
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: falsein config file. - This is patched in v2025.12.0 by flipping default value of
trustProxytofalse. 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 Due to misconfiguration in 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"}
Impact
An attacker can brute force accounts bypassing rate limiting protection.
The vulnerability can be exploited over the network without needing physical access. It is easy for an attacker to exploit this vulnerability. An attacker does not need any special privileges or access rights. No user interaction is needed for the attacker to exploit this vulnerability. The impact is confined to the system where the vulnerability exists. There is a low impact on the integrity of the data. There is a low impact on the availability of the system.
Exploitation attempts have been detected. Elevated vigilance and prompt remediation are advised.
The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.
We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.
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