Security readout for executives and security teams
Plain-English summary
CVE-2021-33820 describes a denial-of-service issue in the UniFi Protect G3 FLEX Camera firmware UVC.v4.30.0.67. An attacker can overwhelm the camera web service with excessive TCP SYN traffic, making the web server unavailable. The provided sources do not identify data theft, code execution, or a vendor patch.
Executive priority
Prioritize remediation where affected cameras support security monitoring, physical access control, or executive facilities. Business risk is primarily loss of camera management or visibility, not confirmed compromise of data or systems.
Technical view
The CVE states that the camera web service can exhaust resources when receiving a large volume of TCP SYN packets, resulting in denial of service. The record names UniFi Protect G3 FLEX Camera version UVC.v4.30.0.67. Public metadata lacks CVSS, CWE, CPE, and remediation details.
Likely exposure
Exposure is most likely for organizations running UniFi Protect G3 FLEX cameras on firmware UVC.v4.30.0.67, especially where the camera web service is reachable from untrusted networks or weakly segmented internal networks.
Exploitation context
The source bundle includes a public proof-of-concept reference, but KEV is false and no cited source claims active exploitation. Treat this as publicly documented DoS risk, not confirmed in-the-wild exploitation.
Researcher notes
Evidence is sparse. The CVE description supports TCP SYN resource exhaustion against the camera web service, but no CVSS, CWE, affected CPE, patch version, or vendor advisory is present in the provided bundle.
Mitigation direction
- Check Ubiquiti guidance for fixed firmware or recommended configuration changes.
- Restrict camera web access to trusted management networks only.
- Place cameras on segmented networks with limited inbound access.
- Use firewall or network controls to rate-limit abnormal SYN traffic.
- Monitor camera availability and network traffic for sudden SYN spikes.
Validation and detection
- Inventory UniFi Protect G3 FLEX cameras and record firmware versions.
- Confirm whether any device runs UVC.v4.30.0.67.
- Review whether camera web services are reachable from untrusted networks.
- Check firewall and monitoring data for abnormal SYN volume.
- Avoid live flood testing against production cameras.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CVE-2021-33820 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Unknown
- CVSS
- Not scored
- Known Exploited
- No
- Published
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS and timeline data
No CVSS vectors or timeline events were available in the normalized CVE source material.
Source materials
- CVE List V5 sourceCVE List V5
- https://store.ui.com/collections/unifi-protect-cameras/products/unifi-video-g3-flex-cameraCVE reference · x_refsource_MISC
- https://linuxhint.com/hping3/CVE reference · x_refsource_MISC
- https://github.com/Jian-Xian/CVE-POC/blob/master/CVE-2021-33820.mdCVE reference · x_refsource_MISC
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.