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CVE-2026-31849 is a Cross-Site Request Forgery (CSRF) vulnerability discovered in the administrative web interface of the Nexxt Solutions Nebula 300+ router. The core of the issue is that the firmware, in versions up to 12.01.01.37, does not implement any CSRF protections on state-changing endpoints. This means any request that modifies system settings, such as those to `/goform/setSysTools` or other administrative interfaces, is processed solely based on the presence of an active session cookie.
The attack works by leveraging the authenticated session an administrator has established with the device. An attacker can craft a malicious website or send a phishing link that, when visited by the victim, triggers a hidden request to the Nebula 300+ management interface. Because the browser automatically includes the valid session cookie with the request, the device’s backend has no way to distinguish this forged request from a legitimate one initiated by the administrator themselves. The `SameSite=Lax` attribute on the session cookie is intended to mitigate such attacks, but it fails to protect against top-level navigations using `GET` requests, or when an attacker can control sibling subdomains.
This vulnerability is particularly severe because the administrative UI controls critical security functions, including modifying device configuration, enabling or disabling services, and changing security-relevant settings. An attacker exploiting this flaw could, without the administrator’s knowledge or consent, completely reconfigure the device, potentially intercepting or disrupting network traffic, or using the device as a foothold for further attacks on the internal network. The impact is escalated by the fact that the attacker requires no prior authentication; the attack is launched against an already-authenticated administrator session. The root cause is the application’s failure to use a synchronizer token pattern or other industry-standard CSRF defenses, such as checking for custom headers or tokens submitted alongside the request.
DailyCVE Form:
Platform: Nexxt Solutions Nebula 300+
Version: Firmware ≤12.01.01.37
Vulnerability : Missing CSRF Protection
Severity: 6.5 (MEDIUM)
Date: 2026-03-23
Prediction: Vendor firmware update
What Undercode Say:
Analytics from security monitoring platforms indicate ongoing exploitation attempts against this flaw. Below are command snippets for detection and validation:
Search HTTP logs for suspicious POST requests to administrative endpoints grep -E "POST /goform/setSysTools" /var/log/nginx/access.log Use curl to test for CSRF vulnerability (requires a valid session cookie) curl -X POST "https://192.168.1.1/goform/setSysTools" \ -H "Cookie: session_id=<VALID_ADMIN_SESSION>" \ -d "param1=value1¶m2=malicious"
Exploit:
A simple HTML page hosted on an attacker’s server can force the victim’s browser to send a forged request:
<html> <body> <form action="https://192.168.1.1/goform/setSysTools" method="POST"> <input type="hidden" name="param" value="malicious_value"> <input type="submit" value="Click here"> </form> <img src="https://192.168.1.1/goform/setSysTools?param=malicious_value" style="display:none;"> </body> </html>
If the victim is logged into the Nebula 300+ admin interface, the form submission or the image load will automatically include the session cookie, executing the attacker’s command.
Protection:
- Firmware Update: The primary mitigation is to update to the latest firmware version that includes CSRF protections.
- Web Application Firewall (WAF): Deploy a WAF rule to block requests to sensitive endpoints that lack an expected `Referer` or `Origin` header.
- Configuration: Restrict administrative access to a dedicated management VLAN to limit exposure.
- User Awareness: Train administrators to avoid clicking suspicious links while logged into the device.
Impact:
Successful exploitation allows an attacker to perform any administrative action the victim is authorized to do. This includes:
– Changing the device’s configuration, including DNS settings, firewall rules, or VPN credentials.
– Enabling or disabling critical network services.
– Extracting sensitive information from the device.
– Using the compromised device as a pivot point to attack other hosts on the internal network.
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Sources:
Reported By: github.com
Extra Source Hub:
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