How severe is CVE-2021-34418?

CVE-2021-34418 has a CVSS 3.x base score of 4.0, rated medium severity. It is exploitable over local access with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability low.

Is CVE-2021-34418 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (45th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-34418?

CVE-2021-34418 primarily affects Zoom Zoom On-premise Meeting Connector Controller. In total, 5 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-34418?

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

When was CVE-2021-34418 published?

CVE-2021-34418 was published on 2021-11-11 and last updated on 2026-06-17.

CVE-2021-34418

CVE-2021-34418 is a medium-severity vulnerability in Zoom Zoom On-premise Meeting Connector Controller with a CVSS 3.x base score of 4.0. 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-476.

Key facts

Severity: Medium (CVSS 3.x base score 4.0)
CVSS v2: 5.0
EPSS exploit prediction: 1% (45th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-476
Affected product: Zoom Zoom On-premise Meeting Connector Controller
Published: 2021-11-11
Last modified: 2026-06-17

Description

The login routine of the web console in the Zoom On-Premise Meeting Connector before version 4.6.239.20200613, Zoom On-Premise Meeting Connector MMR before version 4.6.239.20200613, Zoom On-Premise Recording Connector before version 3.8.42.20200905, Zoom On-Premise Virtual Room Connector before version 4.4.6344.20200612, and Zoom On-Premise Virtual Room Connector Load Balancer before version 2.5.5492.20200616 fails to validate that a NULL byte was sent while authenticating. This could lead to a crash of the login service.

Frequently asked questions

What is CVE-2021-34418?: The login routine of the web console in the Zoom On-Premise Meeting Connector before version 4.6.239.20200613, Zoom On-Premise Meeting Connector MMR before version 4.6.239.20200613, Zoom On-Premise Recording Connector before version 3.8.42.20200905, Zoom On-Premise Virtual Room Connector before version 4.4.6344.20200612, and Zoom On-Premise Virtual Room Connector Load Balancer before version 2.5.5492.20200616 fails to validate that a NULL byte was sent while authenticating. This could lead to a crash of the login service.
How severe is CVE-2021-34418?: CVE-2021-34418 has a CVSS 3.x base score of 4.0, rated medium severity. It is exploitable over local access with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability low.
Is CVE-2021-34418 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (45th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-34418?: CVE-2021-34418 primarily affects Zoom Zoom On-premise Meeting Connector Controller. In total, 5 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-34418?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-34418 published?: CVE-2021-34418 was published on 2021-11-11 and last updated on 2026-06-17.

References

https://explore.zoom.us/en/trust/security/security-bulletin

Affected products (5)

cpe:2.3:a:zoom:zoom_on-premise_meeting_connector_controller:*:*:*:*:*:*:*:*
cpe:2.3:a:zoom:zoom_on-premise_meeting_connector_mmr:*:*:*:*:*:*:*:*
cpe:2.3:a:zoom:zoom_on-premise_recording_connector:*:*:*:*:*:*:*:*
cpe:2.3:a:zoom:zoom_on-premise_virtual_room_connector:*:*:*:*:*:*:*:*
cpe:2.3:a:zoom:zoom_on-premise_virtual_room_connector_load_balancer:*:*:*:*:*:*:*:*

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