Vulnerability · Published Dec 15, 2025 · Assigned by GitHub_M
CVE-2025-66482Misskey has a login rate limit bypass via spoofed X-Forwarded-For header
Medium 6.9
In plain English
A medium-severity security flaw in misskey from misskey-dev. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 27% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
Misskey is an open source, federated social media platform. Attackers who use an untrusted reverse proxy or not using a reverse proxy at all 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-alpha.2, making it still vulnerable if the configuration is not set correctly. This is patched in v2025.12.0-alpha.2 by flipping default value of `trustProxy` to `false`. Users of a trusted reverse proxy who are unsure if they manually overode this value should check their config for optimal behavior. Users are running Misskey with a trusted reverse proxy should not be affected by this vulnerability. From v2025.9.1 to v2025.11.1, workaround is available. Set `trustProxy: false` in config file.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| npm | misskey-js | 2025.12.0-alpha.2 | GHSA-wwrj-3hvj-prpm |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| misskey-dev | misskey | >= 2025.9.1, < 2025.12.0-alpha.2 |
Weakness: CWE-307, CWE-1188 · Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N