CVE-2025-25306
📋 TL;DR
This vulnerability in Misskey allows attackers to forge ActivityPub objects by manipulating the relationship between 'id' and 'url' fields, bypassing authorization checks. It affects all Misskey instances running vulnerable versions, potentially enabling unauthorized actions. The issue stems from insufficient validation of the patch for CVE-2024-52591.
💻 Affected Systems
- Misskey
📦 What is this software?
Misskey by Misskey
⚠️ Risk & Real-World Impact
Worst Case
Complete account takeover, unauthorized content manipulation, or federation-wide impersonation attacks across the ActivityPub network.
Likely Case
Unauthorized posting, content deletion, or account manipulation on vulnerable Misskey instances.
If Mitigated
Limited impact with proper input validation and ActivityPub object verification in place.
🎯 Exploit Status
Exploitation requires understanding of ActivityPub protocol and object structure, but no authentication is needed.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 2025.2.1
Vendor Advisory: https://github.com/misskey-dev/misskey/security/advisories/GHSA-6w2c-vf6f-xf26
Restart Required: Yes
Instructions:
1. Backup your Misskey instance. 2. Update to version 2025.2.1 via git pull or package manager. 3. Run 'pnpm install' to update dependencies. 4. Restart the Misskey service.
🔧 Temporary Workarounds
Temporary ActivityPub Filtering
allImplement network filtering to block suspicious ActivityPub objects with mismatched id/url fields
🧯 If You Can't Patch
- Implement strict input validation for all ActivityPub objects
- Monitor logs for suspicious ActivityPub object patterns and block offending sources
🔍 How to Verify
Check if Vulnerable:
Check if Misskey version is earlier than 2025.2.1Check Version:
Check package.json or run 'git log --oneline -1' in Misskey directoryVerify Fix Applied:
Confirm version is 2025.2.1 or later and test ActivityPub object validation📡 Detection & Monitoring
Log Indicators:
- Unusual ActivityPub object processing
- Authorization bypass attempts in ActivityPub handlers
Network Indicators:
- Suspicious ActivityPub payloads with manipulated id/url fields
SIEM Query:
source="misskey" AND ("ActivityPub" OR "authorization bypass")