How severe is CVE-2020-21733?

CVE-2020-21733 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-2020-21733 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (58th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2020-21733?

CVE-2020-21733 affects Sagemcom F@st 3686 Firmware. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2020-21733?

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

When was CVE-2020-21733 published?

CVE-2020-21733 was published on 2020-09-14 and last updated on 2026-07-09.

CVE-2020-21733

CVE-2020-21733 is a medium-severity vulnerability in Sagemcom F@st 3686 Firmware with a CVSS 3.x base score of 6.1. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. 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: 1% (58th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-79
Affected product: Sagemcom F@st 3686 Firmware
Published: 2020-09-14
Last modified: 2026-07-09

Description

Sagemcom F@ST3686 v1.0 HUN 3.97.0 has XSS via RgDiagnostics.asp, RgDdns.asp, RgFirewallEL.asp, RgVpnL2tpPptp.asp.

Frequently asked questions

What is CVE-2020-21733?: Sagemcom F@ST3686 v1.0 HUN 3.97.0 has XSS via RgDiagnostics.asp, RgDdns.asp, RgFirewallEL.asp, RgVpnL2tpPptp.asp.
How severe is CVE-2020-21733?: CVE-2020-21733 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-2020-21733 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (58th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2020-21733?: CVE-2020-21733 affects Sagemcom F@st 3686 Firmware. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2020-21733?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2020-21733 published?: CVE-2020-21733 was published on 2020-09-14 and last updated on 2026-07-09.

References

Affected products (1)

cpe:2.3:o:sagemcom:f\@st_3686_firmware:1.0_hun_3.97.0:*:*:*:*:*:*:*

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