CVE-2021-21804

Name: CVE-2021-21804
Creator: NVD / NIST
Published: 2021-07-16T11:15:09.867+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

CRITICALCVSS 9.8/10EPSS 3.71%

Last modified Jun 17, 2026

CVE-2021-21804 is a critical-severity vulnerability rated 9.8/10 on the CVSS scale. A local file inclusion (LFI) vulnerability exists in the options.php script functionality of Advantech R-SeeNet v 2.4.12 (20.10.2020). A specially crafted HTTP request can lead to arbitrary PHP code execution. EPSS estimates a 3.71% chance of exploitation in the next 30 days.

Description

A local file inclusion (LFI) vulnerability exists in the options.php script functionality of Advantech R-SeeNet v 2.4.12 (20.10.2020). A specially crafted HTTP request can lead to arbitrary PHP code execution. An attacker can send a crafted HTTP request to trigger this vulnerability.

Metrics

CVSS 3.1

9.8/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS Probability

3.71%

88.4th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Advantech	R-Seenet	2.4.12

References

https://talosintelligence.com/vulnerability_reports/TALOS-2021-1273Exploit, Third Party Advisory
https://talosintelligence.com/vulnerability_reports/TALOS-2021-1273Exploit, Third Party Advisory

Timeline

Published: Jul 16, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-21804?

How severe is CVE-2021-21804?

CVE-2021-21804 has a CVSS score of 9.8/10 (CRITICAL severity). The EPSS model estimates a 3.71% probability of exploitation in the next 30 days.

How do I fix CVE-2021-21804?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-21804?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST