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Fencer Vulns
critical 9.6

CVE-2021-21800 in the critical feed json

Cross-site scripting vulnerabilities exist in the ssh_form.php script functionality of Advantech R-SeeNet v 2.4.12 (20.10.2020).

published 2021-07-16 5 y ago modified 2026-06-17 4 mo ago also EUVD-2021-8972

cvss
9.6
version 3.0, CNA
cisa kev
Not listed
not in CISA's catalog
epss
14.1%
EPSS 14.1% chance of exploitation in 30 days, percentile 96%
public exploits
0
none known, plus a Nuclei check

Summary

Cross-site scripting vulnerabilities exist in the ssh_form.php script functionality of Advantech R-SeeNet v 2.4.12 (20.10.2020). If a user visits a specially crafted URL, it can lead to arbitrary JavaScript code execution in the context of the targeted user’s browser. An attacker can provide a crafted URL to trigger this vulnerability.

Exploit prediction

14.12% chance of exploitation in the next 30 days, higher than 96% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • Nuclei template Advantech R-SeeNet 2.4.12 - Cross-Site Scripting nuclei detection template
  • talosintelligence.com https://talosintelligence.com/vulnerability_reports/TALOS-2021-1271 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.0 9.6 CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H
NVD 3.1 6.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
NVD 2.0 4.3 AV:N/AC:M/Au:N/C:N/I:P/A:N

Affected products

  • n/a Advantech

Classification

Weakness
  • CWE-79 Improper Neutralization of Input During Web Page Generation

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.