CVE-2025-66402 [High] | Security Vulnerability in Misskey

CVE-2025-66402 is rated Exploit Available (50/100): CVSS High severity, with low exploitation likelihood (EPSS 0.04%). 1 public exploit reference(s) are indexed (Exploit-DB). Public exploits are available—assess exposure, apply mitigations, and prioritize patching.

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

EDB-ID

Source

Kind

Published

Link

—

nvd_ref

exploit_tag

Exploit-DB ↗

#	Date	Old EPSS score	New EPSS score	Delta (New - Old)
1	2026-05-13	0.05%	0.04%	-0.01%
2	2026-04-16	0.04%	0.05%	+0.02%
3	2025-12-16	—	0.04%	—

Date

Old EPSS score

New EPSS score

Delta (New - Old)

2026-05-13

0.05%

0.04%

-0.01%

2026-04-16

0.04%

0.05%

+0.02%

2025-12-16

—

0.04%

—

Base score	Version	Severity	Vector	Exploitability	Impact	Score source
7.1	4.0	HIGH	`CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:N/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:L) Low privileges are required. User interaction (UI:N) No user interaction is required. Vulnerable system confidentiality impact (VC:H) High confidentiality impact on the vulnerable system. Vulnerable system integrity impact (VI:N) No integrity impact on the vulnerable system. Vulnerable system availability impact (VA:N) No 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:L/UI:N/S:U/C:H/I:N/A:N` 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:L) A normal user session is enough; they don’t have to be admin. 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:H) Serious risk that confidential data gets exposed in a big way. Integrity (I:N) Data isn’t meaningfully altered or forged. Availability (A:N) Service keeps running; no real outage angle.	2.8	3.6	[email protected]

Base score

Version

Severity

Vector

Exploitability

Impact

Score source

7.1

4.0

HIGH

CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:N/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:L): Low privileges are required.
User interaction (UI:N): No user interaction is required.
Vulnerable system confidentiality impact (VC:H): High confidentiality impact on the vulnerable system.
Vulnerable system integrity impact (VI:N): No integrity impact on the vulnerable system.
Vulnerable system availability impact (VA:N): No 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:L/UI:N/S:U/C:H/I:N/A:N 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:L): A normal user session is enough; they don’t have to be admin.
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:H): Serious risk that confidential data gets exposed in a big way.
Integrity (I:N): Data isn’t meaningfully altered or forged.
Availability (A:N): Service keeps running; no real outage angle.

2.8

3.6

[email protected]

Affected software / configurations for CVE-2025-66402

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-2025-66402

URL	Tags
https://github.com/misskey-dev/misskey/commit/dc77d59f8712d3fe0b73cd4af2035133839cd57b	Patch
https://github.com/misskey-dev/misskey/security/advisories/GHSA-496g-mmpw-j9x3	Exploit Vendor Advisory

URL

CVE-2025-66402 | misskey.js's export data contains private post data

Public exploit references (Exploit-DB) for CVE-2025-66402

Exploit prediction scoring system (EPSS) score for CVE-2025-66402

Common vulnerability scoring system (CVSS) metrics for CVE-2025-66402

Weakness enumeration for CVE-2025-66402

GitHub Security Advisory for CVE-2025-66402

Affected software / configurations for CVE-2025-66402

References for CVE-2025-66402