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Misskey CVE-2024-25636

HIGH
Unrestricted Upload of File with Dangerous Type (CWE-434)
2024-02-19 security-advisories@github.com
8.8
CVSS 3.1 · NVD
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Vulnerability Assessment

Weakness
CWE
OWASP Top 10:2025
A06:2025 - Insecure Design
ASVS 5.0
V5 - File Handling File type validation, storage isolation
MITRE ATT&CK

2 techniques across 2 tactics: Command and Control, Persistence

The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up.

Impact

CVSS score of 8.8 (HIGH). Attack characteristics: network attack vector, low complexity, low privileges required, no user interaction not required.

Exploit ScenarioDerived

A remote attacker could upload malicious files that can be executed on the server by sending crafted requests to the affected application.

This Week Schedule remediation this week. Why: HIGH severity (CVSS 7.0-8.9).
Patch available 0.7% exploitation probability (EPSS)

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AnalysisAI

Misskey is an open source, decentralized social media platform with ActivityPub support. Rated high severity (CVSS 8.8), this vulnerability is remotely exploitable, low attack complexity. This Unrestricted File Upload vulnerability could allow attackers to upload malicious files that can be executed on the server.

RemediationAI

A vendor patch is available. Apply the latest security update as soon as possible. Validate file types server-side, store uploads outside webroot, use random filenames, scan for malware.

Affects your stack

Find out whether the stacks and servers you run are on an affected version.

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

This vulnerability is classified as Unrestricted File Upload (CWE-434), which allows attackers to upload malicious files that can be executed on the server. Misskey is an open source, decentralized social media platform with ActivityPub support. Prior to version 2024.2.0, when fetching remote Activity Streams objects, Misskey doesn't check that the response from the remote server has a Content-Type header value of the Activity Streams media type, which allows a threat actor to upload a crafted Activity Streams document to a remote server and make a Misskey instance fetch it, if the remote server accepts arbitrary user uploads. The vulnerability allows a threat actor to impersonate and take over an account on a remote server that satisfies all of the following properties: allows the threat actor to register an account; accepts arbitrary user-uploaded documents and places them on the same domain as legitimate Activity Streams actors; and serves user-uploaded document in response to requests with an Accept header value of the Activity Streams media type. Version 2024.2.0 contains a patch for the issue. Affected products include: Misskey. Version information: version 2024.2.0.

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  • Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

NVD PRIMARY 8.8 HIGH
AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

DescriptionNVD

Misskey is an open source, decentralized social media platform with ActivityPub support. Prior to version 2024.2.0, when fetching remote Activity Streams objects, Misskey doesn't check that the response from the remote server has a Content-Type header value of the Activity Streams media type, which allows a threat actor to upload a crafted Activity Streams document to a remote server and make a Misskey instance fetch it, if the remote server accepts arbitrary user uploads. The vulnerability allows a threat actor to impersonate and take over an account on a remote server that satisfies all of the following properties: allows the threat actor to register an account; accepts arbitrary user-uploaded documents and places them on the same domain as legitimate Activity Streams actors; and serves user-uploaded document in response to requests with an Accept header value of the Activity Streams media type. Version 2024.2.0 contains a patch for the issue.

Threat Intelligence Overview

EPSS Score
0.7%
Top 53% exploitable
Data Quality
3 sources
Confidence: Low

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity HIGH
CISA KEV No
Public POC No
EPSS 0.7%
Patch available Yes
Active threat No
Deciding rule
HIGH severity (CVSS 7.0-8.9)
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived
Scheduled
Exploitation· derived
None
System Exposure· derived
Open
Automatable· derived
No
Human Impact· derived
Medium

Priority Score

45
Low Medium High Critical
KEV: 0
EPSS: +1
CVSS: +44
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Malicious file upload attacks exploit insufficient validation when web applications accept user-provided files.

Affected Products (CPE)NVD

cpe:2.3:a:misskey:misskey:*:*:*:*:*:*:*:*
CVE-2024-32983 HIGH POC
7.5 Jun 03

Misskey is an open source, decentralized microblogging platform. Rated high severity (CVSS 7.5), this vulnerability is r

CVE-2025-66402 HIGH POC
7.1 Dec 16

Missing authorization checks in Misskey's favorites and clips export feature allow any authenticated user to read the co

CVE-2025-66482 MEDIUM POC
6.9 Dec 16

Login rate-limit bypass in Misskey (versions 2025.9.1 through 2025.11.x, and up to but not including 2025.12.0-alpha.2)

CVE-2019-1020010 MEDIUM POC
6.1 Jul 29

Misskey before 10.102.4 allows hijacking a user's token. Rated medium severity (CVSS 6.1), this vulnerability is remotel

CVE-2023-24812 CRITICAL
9.8 Feb 22

Misskey is an open source, decentralized social media platform. Rated critical severity (CVSS 9.8), this vulnerability i

CVE-2023-52139 CRITICAL
9.6 Dec 29

Misskey is an open source, decentralized social media platform. Rated critical severity (CVSS 9.6), this vulnerability i

CVE-2025-46559 MEDIUM POC
5.4 May 05

Misskey is an open source, federated social media platform. Rated medium severity (CVSS 5.4), this vulnerability is remo

CVE-2026-46713 CRITICAL
9.2 Aug 03

Signature validation bypass in Misskey (versions 12.37.0 through prior to 2026.5.4) allows an attacker to have spoofed A

CVE-2026-47746 HIGH
8.9 Aug 03

JSON-LD signature validation in Misskey's ActivityPub federation layer accepts fraudulent federated activities due to a

CVE-2024-52591 HIGH
8.8 Dec 18

Misskey is an open source, federated social media platform. Rated high severity (CVSS 8.8), this vulnerability is remote

CVE-2024-52590 HIGH
8.8 Dec 18

Misskey is an open source, federated social media platform. Rated high severity (CVSS 8.8), this vulnerability is remote

CVE-2026-104816 HIGH
8.5 Oct 13

Client-side DOM cross-site scripting in Misskey's RSS widgets lets an attacker who controls or can inject into a feed th

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