CVE-2025-49090
📋 TL;DR
This vulnerability in the Matrix specification before version 1.16 allows attackers to manipulate room state resolution, potentially enabling unauthorized modifications to chat room permissions, membership, and configuration. It affects any Matrix server implementation using room versions before 12 and state resolution algorithms before 2.1.
💻 Affected Systems
- Matrix server implementations (Synapse, Dendrite, Conduit, etc.)
- Matrix clients that implement server logic
⚠️ Manual Verification Required
This CVE does not have specific version information in our database, so automatic vulnerability detection cannot determine if your system is affected.
Why? The CVE database entry doesn't specify which versions are vulnerable (no version ranges provided by the vendor/NVD).
🔒 Custom verification scripts are available for registered users. Sign up free to download automated test scripts.
- Review the CVE details at NVD
- Check vendor security advisories for your specific version
- Test if the vulnerability is exploitable in your environment
- Consider updating to the latest version as a precaution
⚠️ Risk & Real-World Impact
Worst Case
Attackers could take over chat rooms, impersonate users, censor messages, or exfiltrate sensitive conversations by manipulating room state.
Likely Case
Malicious actors could disrupt room operations, modify permissions, or manipulate room membership in targeted attacks.
If Mitigated
With proper patching, the risk is eliminated as the state resolution algorithm is fundamentally fixed.
🎯 Exploit Status
Exploitation requires understanding of Matrix state resolution algorithms and ability to send crafted events to rooms.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Matrix specification v1.16+
Vendor Advisory: https://matrix.org/blog/2025/08/security-release/
Restart Required: Yes
Instructions:
1. Update Matrix server to version supporting specification v1.16+ 2. Ensure room version 12+ is used 3. Implement state resolution algorithm 2.1+ 4. Restart Matrix services
🔧 Temporary Workarounds
Migrate rooms to version 12+
linuxForce all rooms to use room version 12 or higher which includes the fixed state resolution algorithm
matrix-synapse-admin migrate-room <room_id> 12
🧯 If You Can't Patch
- Implement network segmentation to isolate Matrix servers from untrusted networks
- Monitor for unusual room state changes and implement alerting for suspicious modifications
🔍 How to Verify
Check if Vulnerable:
Check Matrix server logs for room versions below 12 and specification version below 1.16Check Version:
matrix-synapse --version or check server configuration for specification versionVerify Fix Applied:
Verify server reports using specification v1.16+ and all rooms are at version 12+📡 Detection & Monitoring
Log Indicators:
- Unusual state event sequences
- Rapid room state changes
- Permission modifications from unexpected users
Network Indicators:
- Abnormal volume of state events
- Patterns of room join/leave events
SIEM Query:
source="matrix-server" AND (event_type="m.room.power_levels" OR event_type="m.room.member") | stats count by user_id, room_id