CVE-2025-31700: Dahua Products Buffer Overflow Vulnerability

CVE-2025-31700 Overview

A buffer overflow vulnerability has been identified in Dahua products that could allow attackers to cause service disruption or achieve remote code execution. By sending specially crafted malicious packets, attackers can exploit this memory corruption flaw to crash affected devices or potentially execute arbitrary code. While some Dahua devices may have Address Space Layout Randomization (ASLR) protection deployed, which reduces the likelihood of successful code execution attacks, denial-of-service conditions remain a significant concern for affected systems.

Critical Impact

Network-accessible buffer overflow vulnerability that can lead to remote code execution or denial-of-service attacks against Dahua surveillance and security devices.

Affected Products

• Dahua Products (refer to Dahua Security Advisory for complete product list)

Discovery Timeline

• 2025-07-23 - CVE-2025-31700 published to NVD
• 2025-07-25 - Last updated in NVD database

Technical Details for CVE-2025-31700

Vulnerability Analysis

This vulnerability is classified as CWE-120 (Buffer Copy without Checking Size of Input), commonly known as a classic buffer overflow. The flaw exists in how Dahua products process network input, where insufficient bounds checking allows attackers to write data beyond the boundaries of allocated buffers.

The attack requires network access but involves high complexity due to the presence of exploit mitigation technologies like ASLR on some devices. No authentication or user interaction is required to attempt exploitation. If successfully exploited, an attacker could achieve complete compromise of confidentiality, integrity, and availability of the affected system.

Root Cause

The root cause is improper input validation when copying data into fixed-size buffers. When processing network packets, the affected Dahua software fails to verify that incoming data fits within the destination buffer, leading to memory corruption. This classic buffer overflow condition (CWE-120) occurs because the application copies user-supplied input without adequately checking its length against the buffer's capacity.

Attack Vector

The vulnerability is exploitable over the network without requiring authentication or user interaction. An attacker would craft a malicious network packet containing data designed to overflow a buffer in the target Dahua device. The exploitation flow includes:

1. Attacker identifies a vulnerable Dahua device accessible over the network
2. Attacker crafts a specially formatted packet with oversized data intended to overflow specific buffers
3. Upon processing the malicious packet, the device's buffer is overwritten
4. Depending on memory layout and ASLR state, this results in either:
   
   • Service crash (denial-of-service) when critical memory structures are corrupted
   • Remote code execution if the attacker can control the overwritten memory to redirect program flow

The presence of ASLR on some devices makes reliable code execution more difficult, but denial-of-service remains a consistent outcome. Refer to the Dahua Trusted Center Security Advisory for detailed technical information.

Detection Methods for CVE-2025-31700

Indicators of Compromise

• Unexpected service crashes or restarts on Dahua devices
• Anomalous network traffic patterns targeting Dahua device ports
• Memory corruption errors in device logs
• Unusual process terminations or system instability

Detection Strategies

• Monitor network traffic for oversized or malformed packets destined for Dahua devices
• Implement IDS/IPS rules to detect buffer overflow exploitation attempts
• Configure alerts for repeated crashes or service restarts on Dahua equipment
• Enable logging on Dahua devices and centralize logs for analysis

Monitoring Recommendations

• Deploy network monitoring solutions to baseline normal traffic to Dahua devices
• Implement anomaly detection for unusual packet sizes or frequencies
• Monitor device health metrics including memory usage and crash events
• Regularly review security logs from network segments containing Dahua products

How to Mitigate CVE-2025-31700

Immediate Actions Required

• Review the Dahua Security Advisory for patching guidance
• Identify all Dahua devices in your environment and assess exposure
• Implement network segmentation to isolate Dahua devices from untrusted networks
• Apply firewall rules to restrict access to Dahua devices to trusted IP addresses only

Patch Information

Dahua has published security guidance for this vulnerability. Organizations should consult the official Dahua Trusted Center Security Advisory #775 for specific firmware updates and patching instructions applicable to their device models. Apply updates according to Dahua's recommendations as soon as possible.

Workarounds

• Restrict network access to Dahua devices using firewall rules or ACLs
• Place Dahua devices on isolated network segments with limited connectivity
• Disable any unnecessary network services on affected devices
• Implement VPN requirements for remote access to Dahua device management interfaces

Network segmentation example for isolating Dahua devices:

# Example firewall rules to restrict Dahua device access
# Allow only trusted management IP ranges
# Deny all other inbound traffic to Dahua device network segment

# Consult your firewall documentation for specific syntax
# Restrict access to management ports and services
# Monitor and log all connection attempts