How severe is CVE-2021-21799?

CVE-2021-21799 has a CVSS 3.x base score of 6.1, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is low, integrity low, and availability none.

Is CVE-2021-21799 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 12% (96th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-21799?

CVE-2021-21799 affects Advantech R-seenet. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-21799?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2021-21799 published?

CVE-2021-21799 was published on 2021-07-16 and last updated on 2026-06-17.

CVE-2021-21799

CVE-2021-21799 is a medium-severity vulnerability in Advantech R-seenet with a CVSS 3.x base score of 6.1. Its EPSS exploit-prediction score of 12% places it in the 96th percentile, indicating an elevated likelihood of exploitation. The underlying weakness is classified as CWE-79.

Key facts

Severity: Medium (CVSS 3.x base score 6.1)
CVSS v2: 4.3
EPSS exploit prediction: 12% (96th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-79
Affected product: Advantech R-seenet
Published: 2021-07-16
Last modified: 2026-06-17

Description

Cross-site scripting vulnerabilities exist in the telnet_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.

Frequently asked questions

What is CVE-2021-21799?: Cross-site scripting vulnerabilities exist in the telnet_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.
How severe is CVE-2021-21799?: CVE-2021-21799 has a CVSS 3.x base score of 6.1, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is low, integrity low, and availability none.
Is CVE-2021-21799 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 12% (96th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-21799?: CVE-2021-21799 affects Advantech R-seenet. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-21799?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-21799 published?: CVE-2021-21799 was published on 2021-07-16 and last updated on 2026-06-17.

References

https://talosintelligence.com/vulnerability_reports/TALOS-2021-1270

Affected products (1)

cpe:2.3:a:advantech:r-seenet:2.4.12:*:*:*:*:*:*:*

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