CVE-2025-66482Public exploitNetwork attack vector

Login throttling bypass via forged forwarding header

Published Dec 15, 2025 · Updated Dec 15, 2025

Authentication rate-limit bypass in Misskey 2025.9.1 through 2025.12.0-alpha.1 allows remote attackers to evade login throttling. ServerService.launch supplies true to Fastify when trustProxy is omitted, causing attacker-controlled X-Forwarded-For data to become the client IP. Exposure requires no reverse proxy or an untrusted one; forged addresses change the IP key used by SigninApiService, enabling account brute force.

CVSS severity6.9
Medium
EPSS probability0.34%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Authentication rate-limit bypass in Misskey 2025.9.1 through 2025.12.0-alpha.1 allows remote attackers to evade login throttling. ServerService.launch supplies true to Fastify when trustProxy is omitted, causing attacker-controlled X-Forwarded-For data to become the client IP. Exposure requires no reverse proxy or an untrusted one; forged addresses change the IP key used by SigninApiService, enabling account brute force.

The record

CVE
CVE-2025-66482
Published
Dec 15, 2025
Updated
Dec 15, 2025
Vendor
Misskey Project
Product
Misskey
Classifications
CWE-307, CWE-1188, T1110.001
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Dec 15, 2025CVE publishedPublication date reported by the CVE source.
  2. Dec 15, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=>= 2025.9.1, < 2025.12.0-alpha.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Misskey Project · Misskeyversion=>= 2025.9.1, < 2025.12.0-alpha.2

Published CVSS scores

6.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L
6.9GitHub, Inc.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

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-307Improper Restriction of Excessive Authentication Attempts
CWE-1188Initialization of a Resource with an Insecure Default
T1110.001Brute Force: Password Guessing

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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