CVE-2026-6824: Stored XSS in 1xxx Series NVR Devices – Critical Vulnerability Analysis

Technical summary

The vulnerability stems from inadequate input sanitization in specific functional modules of 1xxx series NVR devices. An authenticated attacker with high privileges (PR:H) can inject arbitrary HTML and JavaScript that becomes persistently stored in the device's backend database or configuration. When an administrator or user accesses the affected functionality, the stored payload executes in their browser within the security context of the NVR's web interface. The CVSS vector (CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:H/I:H/A:H) indicates network accessibility, low attack complexity, high privilege requirement, user interaction dependency, scope change across security boundaries, and high impact to confidentiality, integrity, and availability. The vulnerability maps to CWE-79 (Improper Neutralization of Input During Web Page Generation), the canonical weakness for XSS flaws.

Business impact

For organizations operating surveillance infrastructure, this vulnerability presents a multi-faceted risk. An insider or a privileged threat actor could compromise the integrity of security footage, modify device settings without audit trails, or harvest administrator credentials for lateral movement. The stored nature of the attack means the compromise persists across reboots and updates until the malicious payload is discovered and removed. For facilities relying on NVR systems for physical security, compliance, or investigative purposes, the ability to manipulate or exfiltrate recordings directly undermines the trustworthiness of the entire surveillance system. Additionally, scope change (S:C in the CVSS vector) indicates the attacker may be able to impact resources beyond the NVR itself, potentially affecting network segments or integrated security systems.

Affected systems

This vulnerability specifically affects NVR devices in the 1xxx product series. The vendors_products field in the source data is empty, meaning the specific vendor and exact model numbers are not provided in the ground-truth data. Organizations using 1xxx series NVRs should consult the vendor's official security advisory to determine which sub-models and firmware versions are impacted and which have been patched. Devices in this series that have not been updated to a patched firmware version are vulnerable if an attacker can authenticate with administrative credentials.

Exploitability

Exploitation requires an authenticated attacker with high-level administrative privileges (PR:H), which is a significant control that limits the attack surface. However, given that many organizations struggle with credential hygiene and privilege escalation is a common lateral-movement technique, this requirement should not be considered a strong mitigation. The attack complexity is low (AC:L), meaning once an attacker has administrative access, successfully injecting and storing malicious scripts does not require specialized conditions or extensive reconnaissance. User interaction (UI:R) is required for the payload to execute—specifically, a victim administrator must visit the affected pages—but this is a routine administrative task and therefore a relatively weak control. Overall, the vulnerability is moderately difficult to exploit but poses a serious risk in environments where administrative credentials may be compromised or where threat actors already have network access.

Remediation

The primary remediation is to apply the vendor's patched firmware version to affected 1xxx series NVRs. Verify the specific patched version against the vendor's security advisory. Until patches can be applied, implement compensating controls: restrict administrative access to the NVR web interface using firewall rules or VPN requirements, enforce multi-factor authentication for administrative logins if available, and monitor NVR access logs for suspicious activity. Conduct a security audit of stored configurations and administrative settings to detect any injected scripts or unauthorized modifications. If malicious scripts have been detected, perform a factory reset or reinstall the firmware to eliminate the persistent payload. Additionally, review and rotate all administrative credentials for the affected NVRs and any systems they can access.

Patch guidance

Contact the vendor or visit their security advisory portal to identify the patched firmware version for your specific 1xxx series model and current firmware level. Verify the availability and release date of the patch before scheduling deployment. Test the patch in a non-production environment if possible to ensure compatibility with your current configuration, integrations, and backup systems. Plan for a maintenance window, as firmware updates typically require device restart. After patching, verify that the NVR functionality is restored, that no configurations were corrupted, and that recordings are intact. Document the patch application date and version for audit compliance. For devices that cannot be patched immediately, implement the compensating controls outlined in the remediation section.

Detection guidance

Monitor NVR access logs and authentication events for failed login attempts or unusual administrative account activity. Review web server logs and configuration files for unexpected HTML or JavaScript patterns, particularly in any user-supplied fields such as device names, descriptions, or custom labels. Use your security information and event management (SIEM) system to correlate multiple failed login attempts followed by successful administrative access, which could indicate a credential compromise. If you have the ability to inspect the NVR's stored configuration or database, search for common XSS payload markers (e.g., <script>, javascript:, onerror=, onload=). Implement network-level detection by monitoring for large or unusual HTTP POST requests to the NVR's configuration endpoints. Consider periodic manual review of the NVR web interface for visual anomalies or unexpected dialog boxes, which could indicate stored XSS payloads. If your organization has a web application firewall or intrusion detection system, configure it to flag XSS pattern attempts on NVR administrative interfaces.

Why prioritize this

Despite not being on the CISA Known Exploited Vulnerabilities (KEV) catalog, this vulnerability merits high-priority remediation due to its HIGH CVSS score (8.4), the persistent nature of stored XSS, the critical role of NVR systems in physical security infrastructure, and the potential for data exfiltration or tampering. The requirement for administrative privileges reduces immediate threat, but the widespread use of weak or reused credentials in operational technology environments means that privilege assumption is a realistic threat scenario. Organizations should prioritize patching based on network segmentation: NVRs directly accessible from untrusted networks should be patched first, followed by those in restricted administrative networks.

Risk score, explained

The CVSS 3.1 score of 8.4 (HIGH) reflects: (1) Network Attack Vector—the vulnerability is exploitable remotely without physical access; (2) Low Attack Complexity—no special conditions or extensive setup required; (3) High Privilege Requirement—a significant limiting factor that prevents opportunistic exploitation by external, unauthenticated threat actors; (4) Required User Interaction—an administrator must actively visit the affected page, which mitigates the risk but is a routine action; (5) Scope Change—the attack can affect security properties of the system itself and potentially other systems or security domains; and (6) High Impact across Confidentiality, Integrity, and Availability—an attacker can read sensitive data (recordings, credentials), modify device behavior or recordings, and potentially disrupt NVR operation. The score is moderately high rather than critical primarily because of the privilege and user interaction requirements, but the persistent nature and broad impact justify treating it as a significant organizational risk.

Frequently asked questions