Is CVE-2021-21801 actively exploited?

Yes. CVE-2021-21801 is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, which means exploitation in the wild has been confirmed.

Can CVE-2021-21801 be exploited remotely?

The attack vector of CVE-2021-21801 has not been classified yet.

What is the CVSS score of CVE-2021-21801?

CVE-2021-21801 has not received a CVSS score yet.

HOME VULNERABILITIESCVE-2021-21801

UNKNOWNCISA KEVIN THE WILD

CVE-2021-21801

Published: April 11, 2026

EPSS:84.60%probability of exploitation in 30 daysPercentile:99.3th

Official Description

This vulnerability is present in device_graph_page.php script, which is a part of the Advantech R-SeeNet web applications. A specially crafted URL by an attacker and visited by a victim can lead to arbitrary JavaScript code execution.

NVD Source

Technical Analysis

CVE-2021-21801 requires local access, meaning attackers must already have a foothold on the target system.

Exploitation requires some privileges, which limits the exposure to scenarios where an attacker has already gained initial access.

CISA has added CVE-2021-21801 to the Known Exploited Vulnerabilities (KEV) catalog, confirming active exploitation in the wild. U.S. federal agencies are required to patch this within the mandated timeframe, and all organizations should treat remediation as urgent.