CVE-2021-1274Network attack vector

Unauthenticated DoS via vDaemon null dereference

Published Jan 20, 2021 · Updated Nov 12, 2024

A null pointer dereference in Cisco SD-WAN before fixed releases allows remote attackers to cause a denial of service via crafted UDP traffic. The flaw occurs in vDaemon's UDP connection response handling, where a crafted packet reaches a null reference. No authentication or user interaction is required, and successful exploitation interrupts service on the targeted SD-WAN component without reported confidentiality or integrity impact.

CVSS severity8.6
High
EPSS probability1.89%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

A null pointer dereference in Cisco SD-WAN before fixed releases allows remote attackers to cause a denial of service via crafted UDP traffic. The flaw occurs in vDaemon's UDP connection response handling, where a crafted packet reaches a null reference. No authentication or user interaction is required, and successful exploitation interrupts service on the targeted SD-WAN component without reported confidentiality or integrity impact.

The record

CVE
CVE-2021-1274
Published
Jan 20, 2021
Updated
Nov 12, 2024
Vendor
ClamAV
Product
Cisco SD-WAN
Classifications
CWE-476, T1499
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 SD-WANversion=n/a

Published CVSS scores

8.6Cisco PSIRTCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/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.

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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-476NULL Pointer Dereference
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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