CVE-2025-20630
📋 TL;DR
Mattermost Mobile versions up to 2.22.0 contain a type casting vulnerability where posts with attachments containing non-String fields can crash the mobile application. Attackers can exploit this by sending specially crafted posts to channels, causing denial of service for mobile users. This affects all Mattermost Mobile users running vulnerable versions.
💻 Affected Systems
- Mattermost Mobile
📦 What is this software?
Mattermost Mobile by Mattermost
⚠️ Risk & Real-World Impact
Worst Case
Persistent mobile application crashes for all users in targeted channels, disrupting mobile collaboration and potentially causing data loss if users cannot access important messages.
Likely Case
Temporary denial of service for mobile users who receive the malicious post, requiring app restart or reinstallation to restore functionality.
If Mitigated
Minimal impact if mobile users quickly restart the app and administrators remove the malicious post from channels.
🎯 Exploit Status
Exploitation requires ability to post messages to channels (authenticated access). The vulnerability is straightforward to trigger once the malicious post structure is known.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 2.23.0
Vendor Advisory: https://mattermost.com/security-updates
Restart Required: Yes
Instructions:
1. Update Mattermost Mobile app to version 2.23.0 or later via official app stores. 2. Ensure all mobile users update their apps. 3. No server-side changes required.
🔧 Temporary Workarounds
Restrict posting permissions
allLimit who can post messages to channels to reduce attack surface
Monitor for crash reports
allSet up monitoring for mobile app crash reports and investigate spikes
🧯 If You Can't Patch
- Educate users to restart the app if it crashes and report suspicious posts immediately
- Implement strict access controls for posting to channels and monitor for unusual posting patterns
🔍 How to Verify
Check if Vulnerable:
Check mobile app version in app settings. If version is 2.22.0 or earlier, the app is vulnerable.Check Version:
Check app version in Settings > About within the Mattermost Mobile appVerify Fix Applied:
Confirm mobile app version is 2.23.0 or later in app settings. Test that the app no longer crashes when processing various attachment types.📡 Detection & Monitoring
Log Indicators:
- Mobile app crash logs showing unhandled type casting exceptions
- Increased mobile app crash reports from users
Network Indicators:
- Posts with unusual attachment structures being sent to multiple channels
- Pattern of posts followed by mobile user disconnections
SIEM Query:
source="mattermost-mobile" AND (error="type cast" OR error="unhandled exception")