CVE-2021-1301Network attack vector

Authenticated DoS via NETCONF input validation

Published Jan 20, 2021 · Updated Nov 12, 2024

Buffer overflow in Cisco SD-WAN Software allows remote authenticated users to cause a denial of service through the NETCONF subsystem. The system insufficiently validates user-supplied input read while establishing an SSH connection, allowing crafted file data to trigger the overflow. Access requires valid remote authentication, and successful exploitation interrupts the affected device or system without disclosed confidentiality or integrity impact.

CVSS severity6.5
Medium
EPSS probability2.10%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Buffer overflow in Cisco SD-WAN Software allows remote authenticated users to cause a denial of service through the NETCONF subsystem. The system insufficiently validates user-supplied input read while establishing an SSH connection, allowing crafted file data to trigger the overflow. Access requires valid remote authentication, and successful exploitation interrupts the affected device or system without disclosed confidentiality or integrity impact.

The record

CVE
CVE-2021-1301
Published
Jan 20, 2021
Updated
Nov 12, 2024
Vendor
ClamAV
Product
Cisco SD-WAN
Classifications
CWE-20, T1499
Attack vector
network
Privileges
authenticated

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 privilegesauthenticated

What is affected?

ClamAV · Cisco SD-WANversion=n/a

Published CVSS scores

6.5CiscoCVSS:3.1/AV:N/AC:L/PR:L/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.

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No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
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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