CVE-2025-66482 | Misskey has a login rate limit bypass via spoofed X-Forwarded-For header

Exp

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.

Published: 2025-12-16 Last update: 2026-01-06 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2025-66482 is rated Exploit Available (50/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.05%). 1 public exploit reference(s) are indexed (Exploit-DB). Public exploits are available—assess exposure, apply mitigations, and prioritize patching.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Public exploit references (Exploit-DB) for CVE-2025-66482

EDB-ID Source Kind Published Link
— nvd_ref exploit_tag Exploit-DB ↗

Exploit prediction scoring system (EPSS) score for CVE-2025-66482

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-01-16 0.05% 0.05% +0.01%
2 2026-01-07 0.05% 0.05% -0.01%
3 2025-12-21 — 0.05% —

Full EPSS history (4 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2025-66482

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
6.9 4.0 MEDIUM
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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network.
Attack complexity (AC:L)
Exploitation conditions are straightforward and stable.
Attack requirements (AT:N)
No additional preconditions are required beyond normal reachability.
Privileges required (PR:N)
No privileges are required.
User interaction (UI:N)
No user interaction is required.
Vulnerable system confidentiality impact (VC:N)
No confidentiality impact on the vulnerable system.
Vulnerable system integrity impact (VI:L)
Limited integrity impact on the vulnerable system.
Vulnerable system availability impact (VA:L)
Limited availability impact on the vulnerable system.
Subsequent system confidentiality impact (SC:N)
No confidentiality impact on subsequent systems.
Subsequent system integrity impact (SI:N)
No integrity impact on subsequent systems.
Subsequent system availability impact (SA:N)
No availability impact on subsequent systems.
Exploit maturity (threat) (E:X)
Not defined: no reliable threat intelligence; scoring assumes the worst case (equivalent to Attacked).
Confidentiality requirement (CR:X)
Not defined: insufficient information; scoring treats this like High (worst case).
Integrity requirement (IR:X)
Not defined: insufficient information; scoring treats this like High (worst case).
Availability requirement (AR:X)
Not defined: insufficient information; scoring treats this like High (worst case).
Modified attack vector (MAV:X)
Not defined: scoring uses the Base Attack Vector (AV).
Modified attack complexity (MAC:X)
Not defined: scoring uses the Base Attack Complexity (AC).
Modified attack requirements (MAT:X)
Not defined: scoring uses the Base Attack Requirements (AT).
Modified privileges required (MPR:X)
Not defined: scoring uses the Base Privileges Required (PR).
Modified user interaction (MUI:X)
Not defined: scoring uses the Base User Interaction (UI).
Modified vulnerable system confidentiality impact (MVC:X)
Not defined: scoring uses the Base VC metric.
Modified vulnerable system integrity impact (MVI:X)
Not defined: scoring uses the Base VI metric.
Modified vulnerable system availability impact (MVA:X)
Not defined: scoring uses the Base VA metric.
Modified subsequent system confidentiality impact (MSC:X)
Not defined: scoring uses the Base SC metric.
Modified subsequent system integrity impact (MSI:X)
Not defined: scoring uses the Base SI metric.
Modified subsequent system availability impact (MSA:X)
Not defined: scoring uses the Base SA metric.
Safety (supplemental) (S:X)
Not evaluated.
Automatable (supplemental) (AU:X)
Not evaluated.
Recovery (supplemental) (R:X)
Not evaluated.
Value density (supplemental) (V:X)
Not evaluated.
Vulnerability response effort (supplemental) (RE:X)
Not evaluated.
Provider urgency (supplemental) (U:X)
Not evaluated.
 — — [email protected]
6.5 3.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:L)
Attackers could change some data, but it’s limited—not everything goes.
Availability (A:L)
Might cause slowdowns, glitches, or partial disruption—not a full brick.
 3.9 2.5 [email protected]

Weakness enumeration for CVE-2025-66482

GitHub Security Advisory for CVE-2025-66482

GHSA-wwrj-3hvj-prpm · Severity: medium · Ecosystem: npm — Misskey has a login rate limit bypass via spoofed X-Forwarded-For header

Affected software / configurations for CVE-2025-66482

Vendor Product Version Raw CPE
misskey misskey >= 13.1.0, < 2025.12.0 cpe:2.3:a:misskey:misskey:*:*:*:*:*:*:*:*
misskey misskey 13.0.0 cpe:2.3:a:misskey:misskey:13.0.0:-:*:*:*:*:*:*
misskey misskey 13.0.0 cpe:2.3:a:misskey:misskey:13.0.0:beta16:*:*:*:*:*:*
misskey misskey 13.0.0 cpe:2.3:a:misskey:misskey:13.0.0:beta21:*:*:*:*:*:*
misskey misskey 13.0.0 cpe:2.3:a:misskey:misskey:13.0.0:beta22:*:*:*:*:*:*
misskey misskey 13.0.0 cpe:2.3:a:misskey:misskey:13.0.0:beta23:*:*:*:*:*:*
misskey misskey 13.0.0 cpe:2.3:a:misskey:misskey:13.0.0:beta24:*:*:*:*:*:*
misskey misskey 13.0.0 cpe:2.3:a:misskey:misskey:13.0.0:beta25:*:*:*:*:*:*
misskey misskey 13.0.0 cpe:2.3:a:misskey:misskey:13.0.0:beta26:*:*:*:*:*:*
misskey misskey 13.0.0 cpe:2.3:a:misskey:misskey:13.0.0:beta27:*:*:*:*:*:*
misskey misskey 13.0.0 cpe:2.3:a:misskey:misskey:13.0.0:beta28:*:*:*:*:*:*
misskey misskey 13.0.0 cpe:2.3:a:misskey:misskey:13.0.0:beta29:*:*:*:*:*:*
misskey misskey 13.0.0 cpe:2.3:a:misskey:misskey:13.0.0:beta30:*:*:*:*:*:*
misskey misskey 13.0.0 cpe:2.3:a:misskey:misskey:13.0.0:beta31:*:*:*:*:*:*
misskey misskey 13.0.0 cpe:2.3:a:misskey:misskey:13.0.0:beta32:*:*:*:*:*:*
misskey misskey 13.0.0 cpe:2.3:a:misskey:misskey:13.0.0:beta33:*:*:*:*:*:*
misskey misskey 13.0.0 cpe:2.3:a:misskey:misskey:13.0.0:beta34:*:*:*:*:*:*
misskey misskey 13.0.0 cpe:2.3:a:misskey:misskey:13.0.0:beta35:*:*:*:*:*:*
misskey misskey 13.0.0 cpe:2.3:a:misskey:misskey:13.0.0:beta36:*:*:*:*:*:*
misskey misskey 13.0.0 cpe:2.3:a:misskey:misskey:13.0.0:beta37:*:*:*:*:*:*
misskey misskey 13.0.0 cpe:2.3:a:misskey:misskey:13.0.0:beta38:*:*:*:*:*:*
misskey misskey 13.0.0 cpe:2.3:a:misskey:misskey:13.0.0:beta39:*:*:*:*:*:*
misskey misskey 13.0.0 cpe:2.3:a:misskey:misskey:13.0.0:beta40:*:*:*:*:*:*
misskey misskey 13.0.0 cpe:2.3:a:misskey:misskey:13.0.0:beta41:*:*:*:*:*:*
misskey misskey 13.0.0 cpe:2.3:a:misskey:misskey:13.0.0:beta42:*:*:*:*:*:*
misskey misskey 13.0.0 cpe:2.3:a:misskey:misskey:13.0.0:beta43:*:*:*:*:*:*
misskey misskey 13.0.0 cpe:2.3:a:misskey:misskey:13.0.0:rc1:*:*:*:*:*:*
misskey misskey 13.0.0 cpe:2.3:a:misskey:misskey:13.0.0:rc10:*:*:*:*:*:*
misskey misskey 13.0.0 cpe:2.3:a:misskey:misskey:13.0.0:rc11:*:*:*:*:*:*
misskey misskey 13.0.0 cpe:2.3:a:misskey:misskey:13.0.0:rc2:*:*:*:*:*:*
misskey misskey 13.0.0 cpe:2.3:a:misskey:misskey:13.0.0:rc3:*:*:*:*:*:*
misskey misskey 13.0.0 cpe:2.3:a:misskey:misskey:13.0.0:rc4:*:*:*:*:*:*
misskey misskey 13.0.0 cpe:2.3:a:misskey:misskey:13.0.0:rc5:*:*:*:*:*:*
misskey misskey 13.0.0 cpe:2.3:a:misskey:misskey:13.0.0:rc6:*:*:*:*:*:*
misskey misskey 13.0.0 cpe:2.3:a:misskey:misskey:13.0.0:rc7:*:*:*:*:*:*
misskey misskey 13.0.0 cpe:2.3:a:misskey:misskey:13.0.0:rc8:*:*:*:*:*:*
misskey misskey 13.0.0 cpe:2.3:a:misskey:misskey:13.0.0:rc9:*:*:*:*:*:*

References for CVE-2025-66482

cvelogic Threat Intelligence