CVE-2021-1275Network attack vector

Service interruption via API request flooding

Published May 6, 2021 · Updated Nov 8, 2024

Denial of service in Cisco Catalyst SD-WAN Manager allows remote attackers to interrupt service by flooding an exposed API with requests. The affected API handles large request volumes insufficiently, allowing unauthenticated traffic to exhaust service capacity. No credentials or user interaction are required, and successful exploitation makes the affected management system unavailable.

CVSS severity7.5
High
EPSS probability2.07%
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 Cisco Catalyst SD-WAN Manager allows remote attackers to interrupt service by flooding an exposed API with requests. The affected API handles large request volumes insufficiently, allowing unauthenticated traffic to exhaust service capacity. No credentials or user interaction are required, and successful exploitation makes the affected management system unavailable.

The record

CVE
CVE-2021-1275
Published
May 6, 2021
Updated
Nov 8, 2024
Vendor
ClamAV
Product
Cisco Catalyst SD-WAN Manager
Classifications
CWE-20, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 6, 2021CVE publishedPublication date reported by the CVE source.
  2. Nov 8, 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 Catalyst SD-WAN Managerversion=n/a

Published CVSS scores

7.5NISTCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
7.8NISTAV:N/AC:L/Au:N/C:N/I:N/A:C
7.5Cisco Systems, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

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-20Improper Input Validation
T1499Endpoint Denial of Service

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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