Lack of media type verification of Activity Streams objects allows impersonation and takeover of remote accounts
Key facts
- Attack vector
- Network
- Privileges required
- Low
- User interaction
- None
- Attack complexity
- Low
- Impact type
- Code execution
- Confidentiality · integrity · availability
- High · High · High
- Fix status
- Fixed
Attack profile from CVSS 3.1 · NVD. Fix status from CNA. Impact type from CWE-434.
Summary
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.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Total
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| misskey-dev | misskey | before 2024.2.0 | 2024.2.0 | Patch available | CNA |
- misskey Vendormisskey-dev Affected before 2024.2.0 Fixed in 2024.2.0 Patch available CNA
CPE configurations NVD · 1
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:misskey:misskey:*:*:*:*:*:*:*:* | before 2024.2.0 | Vulnerable | misskey-dev |
- cpe:2.3:a:misskey:misskey:*:*:*:*:*:*:*:* Versions before 2024.2.0 Vulnerable ·misskey-dev
Remediation
- Fix · CNA misskey (misskey-dev) Fixed in 2024.2.0
Timeline
- 2026-10-02 Threatist record created from CVE-2024-25636
- 2026-10-13 EPSS moved to the 50th–90th percentile
References
Other 3
- https://github.com/misskey-dev/misskey/blob/2024.2.0-beta.10/packages/backend/src/core/activitypub/ApResolverService.ts#L69-L119
- https://github.com/misskey-dev/misskey/blob/2024.2.0-beta.10/packages/backend/src/core/activitypub/models/ApNoteService.ts#L112-L308
- https://github.com/misskey-dev/misskey/blob/2024.2.0-beta.10/packages/backend/src/server/api/endpoints/ap/show.ts#L125-L143
More misskey-dev Misskey vulnerabilities
- TI-2025-18599 Misskey CSRF vulnerability due to insecure configuration of authentication cookie attributes CVSS 3.1HIGH 8.2
- TI-2025-29081 Misskey CSS Style Injection Vulnerability In `MkUrlPreview` CVSS 3.1HIGH 7.2
- TI-2025-40906 Misskey has a login rate limit bypass via spoofed X-Forwarded-For header CVSS 4.0MEDIUM 6.9
- TI-2025-29276 Misskey Directory Traversal Vulnerability in AiScript via `Mk:api` CVSS 3.1HIGH 7.5
- TI-2025-40839 misskey.js's export data contains private post data CVSS 4.0HIGH 7.1
- TI-2026-22705 Misskey lacks proper authorization checks and input validation CVSS 4.0CRITICAL 9.2
Sources
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences