CVE-2025-1558
📋 TL;DR
Mattermost Mobile Apps versions up to 2.25.0 contain a GIF validation vulnerability that allows attackers to crash the Android application by sending malicious GIFs. This affects all Mattermost Android mobile app users who haven't updated to a patched version. The vulnerability requires an attacker to have the ability to send messages to affected users.
💻 Affected Systems
- Mattermost Mobile App for Android
📦 What is this software?
Mattermost Mobile by Mattermost
⚠️ Risk & Real-World Impact
Worst Case
Denial of service for Mattermost Android users, disrupting team communication and potentially causing repeated application crashes that prevent access to the platform.
Likely Case
Targeted disruption of specific users or channels through crafted GIF messages, causing temporary application instability until the malicious message is removed or the app is updated.
If Mitigated
Minimal impact with proper patch management and user awareness, though some disruption may occur before patches are applied.
🎯 Exploit Status
Exploitation requires message sending privileges but is technically simple once a malicious GIF is crafted. No authentication bypass needed beyond normal message permissions.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: > 2.25.0
Vendor Advisory: https://mattermost.com/security-updates
Restart Required: Yes
Instructions:
1. Update Mattermost Mobile App for Android via Google Play Store. 2. Ensure version is >2.25.0. 3. Restart the application after update.
🔧 Temporary Workarounds
Disable GIF display
allConfigure Mattermost to disable automatic GIF rendering in messages
Restrict message attachments
allLimit who can send GIF attachments through Mattermost permissions
🧯 If You Can't Patch
- Implement network filtering to block GIF attachments at the perimeter
- Educate users to avoid opening GIFs from untrusted sources and report suspicious messages
🔍 How to Verify
Check if Vulnerable:
Check Android app version in Mattermost settings > About. If version is 2.25.0 or lower, the system is vulnerable.Check Version:
Not applicable for mobile apps; check via app settings interfaceVerify Fix Applied:
Confirm Android app version is >2.25.0 in Mattermost settings > About. Test by attempting to send a GIF to verify proper validation.📡 Detection & Monitoring
Log Indicators:
- Multiple application crash logs from Mattermost Android app
- Error logs related to GIF parsing or image validation failures
Network Indicators:
- Unusual patterns of GIF file transfers to Mattermost users
- Multiple users reporting app crashes after receiving specific messages
SIEM Query:
source="mattermost" AND (event="app_crash" OR error="GIF" OR error="image_processing")