CVE-2021-1350Network attack vector

Web UI degradation via unthrottled HTTPS packet flood

Published Jan 20, 2021 · Updated Nov 12, 2024

Denial of service in the Cisco Umbrella web UI allows remote attackers to degrade dashboard performance with sustained HTTPS traffic. The web UI accepts crafted HTTPS packets at a high, sustained rate without sufficient rate-limiting controls. No authentication or user interaction is required, and the demonstrated consequence is degraded web UI performance rather than a crash.

CVSS severity5.3
Medium
EPSS probability1.28%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in the Cisco Umbrella web UI allows remote attackers to degrade dashboard performance with sustained HTTPS traffic. The web UI accepts crafted HTTPS packets at a high, sustained rate without sufficient rate-limiting controls. No authentication or user interaction is required, and the demonstrated consequence is degraded web UI performance rather than a crash.

The record

CVE
CVE-2021-1350
Published
Jan 20, 2021
Updated
Nov 12, 2024
Vendor
ClamAV
Product
Cisco Umbrella Insights Virtual Appliance
Classifications
CWE-770, T1498.001
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 20, 2021CVE publishedPublication date reported by the CVE source.
  2. Nov 12, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=n/a

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

ClamAV · Cisco Umbrella Insights Virtual Applianceversion=n/a

Published CVSS scores

5.3Cisco Systems, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L/E:X/RL:X/RC:X

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-770Allocation of Resources Without Limits or Throttling
T1498.001Network Denial of Service: Direct Network Flood

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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