CVE-2025-56761
📋 TL;DR
Memos 0.22 has a stored XSS vulnerability in upload attachment and user avatar features where uploaded content isn't validated before being served back. Authenticated attackers can inject malicious scripts that execute when viewed by administrators, potentially leading to privilege escalation. Only Memos instances running vulnerable versions with authenticated user access are affected.
💻 Affected Systems
- Memos
📦 What is this software?
Memos by Usememos
⚠️ Risk & Real-World Impact
Worst Case
Administrator account compromise leading to full system takeover, data exfiltration, or deployment of additional malware.
Likely Case
Session hijacking, credential theft, or limited privilege escalation within the Memos application.
If Mitigated
Isolated script execution with minimal impact due to proper content security policies and input validation.
🎯 Exploit Status
Requires authenticated access and social engineering/admin interaction to trigger the stored XSS.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 0.24.0 or later (references show fixes in 0.24.0 and 0.24.4)
Vendor Advisory: https://github.com/usememos/memos/security/advisories
Restart Required: No
Instructions:
1. Backup your Memos data. 2. Update to Memos version 0.24.0 or later. 3. Verify the update was successful by checking the version.
🔧 Temporary Workarounds
Disable file uploads
allTemporarily disable attachment and avatar upload features to prevent exploitation.
Modify Memos configuration to disable file upload functionality
Implement Content Security Policy
allAdd strict CSP headers to limit script execution from untrusted sources.
Add 'Content-Security-Policy' header with script-src 'self' directive
🧯 If You Can't Patch
- Restrict user upload permissions to trusted administrators only
- Implement web application firewall rules to block suspicious upload patterns
🔍 How to Verify
Check if Vulnerable:
Check if running Memos version 0.22 or earlier; review if file uploads bypass content type validation.Check Version:
Check Memos web interface settings or run the memos binary with version flagVerify Fix Applied:
Confirm Memos version is 0.24.0 or later; test file uploads with malicious content to ensure proper validation.📡 Detection & Monitoring
Log Indicators:
- Unusual file upload patterns
- Multiple failed upload attempts with suspicious filenames
- Admin account accessing unexpected uploaded files
Network Indicators:
- HTTP requests with suspicious file uploads containing script tags
- Unusual outbound connections from admin sessions
SIEM Query:
source="memos.log" AND ("upload" OR "attachment") AND ("script" OR "javascript" OR "onerror")