CVE-2023-24811
📋 TL;DR
This CVE describes a cross-site scripting (XSS) vulnerability in Misskey's URL preview function. Attackers can execute arbitrary JavaScript when users load malicious URLs in the 'View in Player' or 'View in Window' previews. All Misskey instances running versions prior to 13.3.2 are affected.
💻 Affected Systems
- Misskey
📦 What is this software?
Misskey by Misskey
⚠️ Risk & Real-World Impact
Worst Case
Attackers could steal session cookies, perform actions as authenticated users, deface content, or redirect users to malicious sites, potentially leading to account compromise and data theft.
Likely Case
Attackers would typically use this to steal session cookies or perform limited actions as the victim user, potentially compromising individual accounts.
If Mitigated
With proper input validation and output encoding, the vulnerability would be prevented, and no JavaScript execution would occur from untrusted URLs.
🎯 Exploit Status
Exploitation requires the victim to interact with a malicious URL preview, but the technical complexity of crafting the exploit is low.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 13.3.2
Vendor Advisory: https://github.com/misskey-dev/misskey/security/advisories/GHSA-vc39-c453-67g3
Restart Required: Yes
Instructions:
1. Backup your Misskey instance. 2. Update to version 13.3.2 using your preferred update method (git pull, package manager, etc.). 3. Restart the Misskey service. 4. Verify the update was successful.
🔧 Temporary Workarounds
Disable vulnerable preview functions
allDisable the 'View in Player' and 'View in Window' URL preview functions to prevent exploitation.
Modify Misskey configuration to disable these features (specific configuration depends on deployment method)
🧯 If You Can't Patch
- Disable URL preview functionality entirely in Misskey configuration
- Implement web application firewall (WAF) rules to block malicious URL patterns and XSS payloads
🔍 How to Verify
Check if Vulnerable:
Check if your Misskey version is below 13.3.2 using the version check command.Check Version:
Check the Misskey admin panel or run: node -e "console.log(require('./package.json').version)" from the Misskey installation directoryVerify Fix Applied:
After updating, verify the version is 13.3.2 or higher and test URL preview functionality with safe test URLs.📡 Detection & Monitoring
Log Indicators:
- Unusual URL patterns in access logs, JavaScript execution errors in browser console logs
Network Indicators:
- Requests to external domains from URL preview functionality, unusual outbound connections
SIEM Query:
Search for patterns like 'view-in-player' or 'view-in-window' in web access logs combined with suspicious URL parameters🔗 References
- https://github.com/misskey-dev/misskey/commit/38f9d1e76428bea47c5944c440eab25428c7d99e
- https://github.com/misskey-dev/misskey/security/advisories/GHSA-vc39-c453-67g3
- https://github.com/misskey-dev/misskey/commit/38f9d1e76428bea47c5944c440eab25428c7d99e
- https://github.com/misskey-dev/misskey/security/advisories/GHSA-vc39-c453-67g3
