CVE-2026-25062
📋 TL;DR
This vulnerability allows attackers to read arbitrary files on Outline servers by exploiting path traversal during JSON import. Attackers can embed sequences like '../' in attachment keys to access sensitive system files. All Outline instances running versions before 1.4.0 are affected.
💻 Affected Systems
- Outline
📦 What is this software?
Outline by Getoutline
⚠️ Risk & Real-World Impact
Worst Case
Complete server compromise through reading sensitive files like SSH keys, configuration files, or database credentials, potentially leading to lateral movement or data exfiltration.
Likely Case
Unauthorized access to sensitive server files containing configuration data, user information, or other application data stored on the filesystem.
If Mitigated
Limited impact if proper file permissions restrict access to sensitive directories, though some application data may still be exposed.
🎯 Exploit Status
Exploitation requires user access to JSON import functionality. The vulnerability is straightforward to exploit once access is obtained.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 1.4.0
Vendor Advisory: https://github.com/outline/outline/security/advisories/GHSA-7r4f-3wjv-83xf
Restart Required: Yes
Instructions:
1. Backup your Outline instance and database. 2. Update to version 1.4.0 or later using your deployment method (Docker, manual install, etc.). 3. Restart the Outline service. 4. Verify the update was successful.
🔧 Temporary Workarounds
Disable JSON Import
allTemporarily disable JSON import functionality to prevent exploitation while planning upgrade.
Restrict Import Permissions
allLimit JSON import capabilities to only trusted administrators.
🧯 If You Can't Patch
- Implement strict file system permissions to limit Outline's access to sensitive directories
- Monitor and audit JSON import activities for suspicious patterns
🔍 How to Verify
Check if Vulnerable:
Check Outline version via admin panel or by examining package.json/version files. If version is below 1.4.0, the system is vulnerable.Check Version:
docker exec outline_container node -p "require('./package.json').version" or check admin panelVerify Fix Applied:
After updating, verify version is 1.4.0 or higher and test JSON import functionality with safe test data.📡 Detection & Monitoring
Log Indicators:
- Unusual JSON import activities
- File read errors for unexpected paths
- Import requests containing '../' sequences
Network Indicators:
- Multiple import requests from single user
- Import payloads with unusual attachment keys
SIEM Query:
source="outline" AND ("import" OR "attachment") AND ("..\/" OR "../" OR "/etc/" OR "/root/")