How severe is CVE-2021-33820?

CVE-2021-33820 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2021-33820 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (78th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-33820?

CVE-2021-33820 affects Ui Camera G3 Flex Firmware. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-33820?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2021-33820 published?

CVE-2021-33820 was published on 2021-06-18 and last updated on 2026-06-17.

CVE-2021-33820

CVE-2021-33820 is a high-severity vulnerability in Ui Camera G3 Flex Firmware with a CVSS 3.x base score of 7.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low.

Key facts

Severity: High (CVSS 3.x base score 7.5)
CVSS v2: 5.0
EPSS exploit prediction: 2% (78th percentile)
Actively exploited: Not listed in CISA KEV
Affected product: Ui Camera G3 Flex Firmware
Published: 2021-06-18
Last modified: 2026-06-17

Description

An issue was discovered in UniFi Protect G3 FLEX Camera Version UVC.v4.30.0.67.Attacker could send a huge amount of TCP SYN packet to make web service's resource exhausted. Then the web server is denial-of-service.

Frequently asked questions

What is CVE-2021-33820?: An issue was discovered in UniFi Protect G3 FLEX Camera Version UVC.v4.30.0.67.Attacker could send a huge amount of TCP SYN packet to make web service's resource exhausted. Then the web server is denial-of-service.
How severe is CVE-2021-33820?: CVE-2021-33820 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2021-33820 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (78th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-33820?: CVE-2021-33820 affects Ui Camera G3 Flex Firmware. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-33820?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2021-33820 published?: CVE-2021-33820 was published on 2021-06-18 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:o:ui:camera_g3_flex_firmware:uvc.v4.30.0.67:*:*:*:*:*:*:*

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CVE-2021-33818 — High (CVSS 7.5): An issue was discovered in UniFi Protect G3 FLEX Camera Version UVC.v4.30.0.67. Attackers can use slowhttptest tool to…

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