CVE-2025-6291
📋 TL;DR
A critical stack-based buffer overflow vulnerability in D-Link DIR-825 router's HTTP POST request handler allows remote attackers to execute arbitrary code or crash the device. This affects all systems running DIR-825 firmware version 2.03. The vulnerability is particularly dangerous because the affected products are no longer supported by the vendor.
💻 Affected Systems
- D-Link DIR-825
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete device compromise, persistent backdoor installation, and lateral movement into connected networks.
Likely Case
Device crash causing denial of service, followed by potential remote code execution for attackers with sufficient skill.
If Mitigated
Limited to denial of service if exploit attempts are blocked at network perimeter, though successful exploitation could still occur.
🎯 Exploit Status
Proof-of-concept exploit code is publicly available on GitHub, making exploitation straightforward for attackers.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: N/A
Vendor Advisory: N/A
Restart Required: No
Instructions:
No official patch is available since D-Link no longer supports this product. The only official fix is to replace the hardware with a supported model.
🔧 Temporary Workarounds
Network Segmentation and Isolation
allIsolate DIR-825 routers from critical networks and restrict access to management interfaces.
Firewall Rule Implementation
allBlock external HTTP access to DIR-825 management interface and restrict internal access to trusted IPs only.
🧯 If You Can't Patch
- Immediately replace DIR-825 routers with supported hardware from any vendor
- If replacement is impossible, isolate devices in dedicated VLANs with strict firewall rules blocking all unnecessary traffic
🔍 How to Verify
Check if Vulnerable:
Check router web interface or use serial console to verify firmware version is 2.03. Devices with this version are vulnerable.Check Version:
Check router web interface at http://[router-ip]/ or use telnet/ssh if enabled: show versionVerify Fix Applied:
Since no patch exists, verification requires confirming device replacement or complete network isolation.📡 Detection & Monitoring
Log Indicators:
- Unusual HTTP POST requests to router management interface
- Multiple connection attempts from single sources
- Router crash/reboot logs
Network Indicators:
- HTTP traffic to router management port (typically 80) with abnormal POST request patterns
- Traffic spikes to router from external IPs
SIEM Query:
source_ip="router_ip" AND http_method="POST" AND (uri_contains="do_file" OR content_length>normal_threshold)🔗 References
- https://github.com/xiaobor123/vul-finds/tree/main/vul-find-dir825-dlink
- https://github.com/xiaobor123/vul-finds/tree/main/vul-find-dir825-dlink#poc
- https://vuldb.com/?ctiid.313293
- https://vuldb.com/?id.313293
- https://vuldb.com/?submit.593937
- https://www.dlink.com/
- https://github.com/xiaobor123/vul-finds/tree/main/vul-find-dir825-dlink
