CVE-2021-47795: GeoVision GeoWebServer RCE Vulnerability

CVE-2021-47795 Overview

GeoVision GeoWebServer 5.3.3 contains multiple critical vulnerabilities including local file inclusion (LFI), cross-site scripting (XSS), and remote code execution capabilities stemming from improper input sanitization. Attackers can exploit the WebStrings.srf endpoint by manipulating path traversal and injection parameters to access sensitive system files and execute malicious scripts. This vulnerability poses significant risks to organizations using GeoVision surveillance and security systems.

Critical Impact

Network-accessible attackers can exploit path traversal sequences to read arbitrary files from the affected system without authentication, potentially exposing sensitive configuration data, credentials, and system files.

Affected Products

• GeoVision GeoWebServer 5.3.3
• GeoVision surveillance software deployments using vulnerable GeoWebServer versions

Discovery Timeline

• 2026-01-16 - CVE-2021-47795 published to NVD
• 2026-01-16 - Last updated in NVD database

Technical Details for CVE-2021-47795

Vulnerability Analysis

This vulnerability is classified as CWE-22 (Improper Limitation of a Pathname to a Restricted Directory), commonly known as path traversal or directory traversal. The flaw exists within the GeoWebServer component of GeoVision's surveillance platform, specifically in how the application handles user-supplied input in the WebStrings.srf endpoint.

The vulnerability allows unauthenticated remote attackers to traverse directory structures and access files outside of the intended web root directory. When combined with the cross-site scripting and remote code execution capabilities documented in this CVE, attackers gain a powerful attack chain that can compromise system confidentiality and integrity.

The network-accessible nature of this vulnerability means that any GeoWebServer instance exposed to the network (or internet) could be targeted without requiring prior authentication or user interaction.

Root Cause

The root cause of this vulnerability lies in insufficient input validation and sanitization within the GeoWebServer application. The WebStrings.srf endpoint fails to properly validate and sanitize user-controlled path parameters, allowing attackers to inject path traversal sequences such as ../ (dot-dot-slash) patterns. This enables bypassing of intended directory restrictions and accessing arbitrary files on the underlying filesystem.

Additionally, the lack of proper output encoding enables cross-site scripting attacks, while insufficient command input validation creates remote code execution possibilities.

Attack Vector

The attack vector is network-based, requiring no authentication or user interaction. Attackers can craft malicious HTTP requests to the vulnerable WebStrings.srf endpoint containing specially crafted path traversal sequences.

A typical attack flow involves:

1. Identifying an exposed GeoWebServer instance (typically running on web-accessible ports)
2. Crafting HTTP requests with path traversal payloads targeting the WebStrings.srf endpoint
3. Manipulating path parameters to escape the web root directory
4. Reading sensitive system files such as configuration files, password files, or other critical data
5. Potentially chaining with XSS or RCE capabilities for further exploitation

The vulnerability allows attackers to read arbitrary files from the system, which could include sensitive configuration data, credentials, or other confidential information. Technical details and proof-of-concept information are available in the Exploit-DB #50211 entry.

Detection Methods for CVE-2021-47795

Indicators of Compromise

• HTTP requests to the WebStrings.srf endpoint containing path traversal sequences such as ../, ..%2f, or ..%5c
• Unusual access patterns to the GeoWebServer application from external IP addresses
• Web server logs showing attempts to access system files outside the web root directory
• Error logs indicating file access attempts to sensitive system paths

Detection Strategies

• Implement web application firewall (WAF) rules to detect and block path traversal patterns in HTTP requests
• Monitor GeoWebServer access logs for requests containing encoded or unencoded directory traversal sequences
• Deploy intrusion detection signatures targeting the vulnerable WebStrings.srf endpoint
• Conduct regular vulnerability scanning of GeoVision deployments to identify unpatched instances

Monitoring Recommendations

• Enable verbose logging on GeoWebServer instances to capture detailed request information
• Set up alerting for HTTP requests containing suspicious patterns such as ../, encoded path separators, or attempts to access known sensitive files
• Monitor network traffic to and from GeoWebServer instances for anomalous patterns
• Review web server logs regularly for indicators of exploitation attempts

How to Mitigate CVE-2021-47795

Immediate Actions Required

• Identify all GeoVision GeoWebServer 5.3.3 installations within your environment
• Restrict network access to GeoWebServer instances using firewall rules, limiting exposure to trusted networks only
• Implement a web application firewall (WAF) with rules to block path traversal attack patterns
• Monitor for exploitation attempts while awaiting vendor patches

Patch Information

Organizations should consult GeoVision's Cybersecurity Information page for official security advisories and patch availability. The VulnCheck Advisory on GeoVision provides additional technical details and mitigation guidance.

Ensure that you are running the latest available version of GeoWebServer and subscribe to GeoVision security notifications for updates on this and related vulnerabilities.

Workarounds

• Place GeoWebServer instances behind a reverse proxy that can filter malicious requests containing path traversal patterns
• Implement network segmentation to isolate surveillance systems from general network access
• Use VPN access for remote management of GeoVision systems rather than exposing them directly to the internet
• Disable or restrict access to the WebStrings.srf endpoint if it is not required for operational purposes

# Example firewall rule to restrict GeoWebServer access (Linux iptables)
# Adjust ports and IP ranges according to your environment
iptables -A INPUT -p tcp --dport 80 -s 192.168.1.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 80 -j DROP