CVE-2026-3788
📋 TL;DR
This CVE-2026-3788 is a server-side request forgery (SSRF) vulnerability in Bytedesk's SpringAIOpenrouterRestController component. Attackers can manipulate the apiUrl parameter to make the server send unauthorized requests to internal systems. This affects all Bytedesk deployments up to version 1.3.9.
💻 Affected Systems
- Bytedesk
📦 What is this software?
Bytedesk by Bytedesk
⚠️ Risk & Real-World Impact
Worst Case
Complete compromise of internal network services, data exfiltration, or lateral movement to critical systems via the vulnerable server as a proxy.
Likely Case
Unauthorized access to internal APIs, metadata services, or cloud instance metadata leading to credential theft and privilege escalation.
If Mitigated
Limited impact with proper network segmentation, but still potential for information disclosure about internal network structure.
🎯 Exploit Status
Exploit has been publicly disclosed and requires minimal technical skill to execute. The vulnerability is in a REST controller making it easily accessible.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 1.4.5.4
Vendor Advisory: https://github.com/Bytedesk/bytedesk/commit/975e39e4dd527596987559f56c5f9f973f64eff7
Restart Required: Yes
Instructions:
1. Backup current configuration and data. 2. Upgrade Bytedesk to version 1.4.5.4 or later. 3. Restart the Bytedesk service. 4. Verify the patch is applied by checking the commit hash 975e39e4dd527596987559f56c5f9f973f64eff7.
🔧 Temporary Workarounds
Network Segmentation
allRestrict outbound network access from the Bytedesk server to only necessary external endpoints.
Input Validation
allImplement strict validation of apiUrl parameter to allow only trusted domains.
🧯 If You Can't Patch
- Implement strict network egress filtering to block requests to internal IP ranges and sensitive endpoints.
- Deploy a web application firewall (WAF) with SSRF protection rules to block malicious apiUrl values.
🔍 How to Verify
Check if Vulnerable:
Check if Bytedesk version is 1.3.9 or earlier and if the SpringAIOpenrouterRestController component is enabled.Check Version:
Check the Bytedesk application properties or admin interface for version information.Verify Fix Applied:
Verify the installed version is 1.4.5.4 or later and check for commit hash 975e39e4dd527596987559f56c5f9f973f64eff7 in the codebase.📡 Detection & Monitoring
Log Indicators:
- Unusual outbound HTTP requests from the Bytedesk server to internal IP addresses or unexpected domains
- Multiple failed attempts to access restricted endpoints via the apiUrl parameter
Network Indicators:
- HTTP requests from Bytedesk server to internal network segments (10.x.x.x, 172.16.x.x, 192.168.x.x)
- Requests to cloud metadata endpoints (169.254.169.254 for AWS)
SIEM Query:
source_ip="bytedesk_server" AND (dest_ip IN (10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16) OR dest_ip="169.254.169.254")🔗 References
- https://github.com/Bytedesk/bytedesk/
- https://github.com/Bytedesk/bytedesk/commit/975e39e4dd527596987559f56c5f9f973f64eff7
- https://github.com/Bytedesk/bytedesk/issues/20
- https://github.com/Bytedesk/bytedesk/issues/20#issue-3993526693
- https://github.com/Bytedesk/bytedesk/issues/20#issuecomment-3976672715
- https://github.com/Bytedesk/bytedesk/releases/tag/v1.4.5.4
- https://vuldb.com/?ctiid.349755
- https://vuldb.com/?id.349755
- https://vuldb.com/?submit.768043
