CVE-2025-8760: INSTAR Camera Buffer Overflow Vulnerability

CVE-2025-8760 Overview

A critical buffer overflow vulnerability has been identified in INSTAR 2K+ and 4K IP cameras running firmware version 3.11.1 Build 1124. The vulnerability exists within the base64_decode function of the fcgi_server component. Attackers can exploit this flaw by manipulating the Authorization header, leading to a buffer overflow condition. This vulnerability can be triggered remotely over the network without any authentication or user interaction.

Critical Impact

This remotely exploitable buffer overflow vulnerability in INSTAR IP cameras could allow attackers to execute arbitrary code, crash the device, or gain unauthorized access to surveillance systems without any authentication requirements.

Affected Products

• INSTAR 2K+ cameras running firmware 3.11.1 Build 1124
• INSTAR 4K cameras running firmware 3.11.1 Build 1124

Discovery Timeline

• 2025-08-13 - CVE CVE-2025-8760 published to NVD
• 2025-08-13 - Last updated in NVD database

Technical Details for CVE-2025-8760

Vulnerability Analysis

This vulnerability is classified as CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer). The fcgi_server component in affected INSTAR IP cameras fails to properly validate the length of Base64-encoded data provided in the HTTP Authorization header before decoding it into a fixed-size buffer.

When the base64_decode function processes an overly long or malformed Authorization header, it writes decoded data beyond the allocated buffer boundaries. This memory corruption can overwrite adjacent memory structures, potentially including return addresses, function pointers, or other critical data structures.

The vulnerability is particularly severe because:

• It requires no authentication to exploit
• It can be triggered remotely over the network
• No user interaction is necessary
• Successful exploitation could lead to complete device compromise

Root Cause

The root cause of this vulnerability lies in insufficient bounds checking within the base64_decode function. The function accepts user-controlled input from the HTTP Authorization header without properly validating that the decoded output will fit within the destination buffer. This is a classic example of an improper input validation flaw leading to a memory safety violation.

The fcgi_server component, which handles FastCGI requests for the camera's web interface, trusts the length of incoming Authorization data without performing adequate sanity checks before the decode operation.

Attack Vector

The attack can be initiated remotely over the network. An attacker would craft a malicious HTTP request containing an oversized or specially crafted Base64-encoded string in the Authorization header. When the vulnerable fcgi_server processes this request, the base64_decode function overflows its destination buffer.

The exploitation flow involves:

1. Identifying an exposed INSTAR IP camera on the network
2. Sending a crafted HTTP request with a malicious Authorization header
3. The fcgi_server component receives and processes the request
4. The base64_decode function writes beyond buffer boundaries
5. Memory corruption occurs, potentially leading to code execution or denial of service

For detailed technical analysis of this vulnerability, refer to the Modzero Security Report.

Detection Methods for CVE-2025-8760

Indicators of Compromise

• Unusual crash logs or service restarts of the fcgi_server process on INSTAR cameras
• HTTP requests with abnormally large Authorization headers targeting camera web interfaces
• Memory corruption artifacts or unexpected behavior in camera web management interfaces
• Network traffic containing oversized Base64-encoded strings in HTTP headers directed at IoT devices

Detection Strategies

• Deploy network intrusion detection rules to identify HTTP requests with excessively long Authorization headers targeting known INSTAR camera IP addresses
• Monitor for repeated connection attempts to camera web interfaces followed by service disruptions
• Implement application-layer firewalls to inspect and limit the size of HTTP headers before they reach IoT devices
• Enable logging on network segments containing surveillance equipment to capture suspicious authentication attempts

Monitoring Recommendations

• Establish baseline network behavior for IP cameras and alert on anomalies such as unexpected outbound connections or service crashes
• Segment surveillance networks and monitor for unauthorized access attempts from untrusted network zones
• Review camera access logs regularly for failed authentication attempts with malformed credentials
• Implement network monitoring to detect scanning activity targeting common IP camera ports

How to Mitigate CVE-2025-8760

Immediate Actions Required

• Isolate affected INSTAR 2K+ and 4K cameras from direct internet exposure by placing them behind a firewall or VPN
• Restrict network access to camera web interfaces to trusted IP addresses only
• Monitor for vendor firmware updates that address this vulnerability
• Consider disabling HTTP-based authentication mechanisms if alternative secure methods are available

Patch Information

At the time of publication, vendor patch information is not available in the CVE data. Organizations should monitor INSTAR's official channels and the Modzero Security Report for updates on security patches. Additional vulnerability details are available through VulDB.

Workarounds

• Place all affected cameras behind a firewall that blocks external access to web management interfaces
• Implement a VPN requirement for remote camera administration to prevent direct exposure
• Use network segmentation to isolate IoT devices from critical network infrastructure
• Deploy a reverse proxy with request filtering to limit Authorization header sizes before they reach cameras

# Example iptables rule to restrict camera web interface access
# Replace 192.168.1.100 with your camera IP and 10.0.0.0/24 with trusted network
iptables -A INPUT -d 192.168.1.100 -p tcp --dport 80 -s 10.0.0.0/24 -j ACCEPT
iptables -A INPUT -d 192.168.1.100 -p tcp --dport 80 -j DROP
iptables -A INPUT -d 192.168.1.100 -p tcp --dport 443 -s 10.0.0.0/24 -j ACCEPT
iptables -A INPUT -d 192.168.1.100 -p tcp --dport 443 -j DROP