CVE-2021-1540Network attack vector

Administrator command execution via nocli authorization bypass

Published Jun 4, 2021 · Updated Nov 7, 2024

Incorrect authorization in Cisco ASR 5000 Series Software allows remote authenticated users to execute restricted CLI commands over SSH. The StarOS authorization path processes non-interactive SSH CLI requests without enforcing the administrator account's nocli restriction. Exploitation requires an administrator account configured with nocli; successful requests expose only a subset of CLI commands.

CVSS severity6.5
Medium
EPSS probability1.05%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Incorrect authorization in Cisco ASR 5000 Series Software allows remote authenticated users to execute restricted CLI commands over SSH. The StarOS authorization path processes non-interactive SSH CLI requests without enforcing the administrator account's nocli restriction. Exploitation requires an administrator account configured with nocli; successful requests expose only a subset of CLI commands.

The record

CVE
CVE-2021-1540
Published
Jun 4, 2021
Updated
Nov 7, 2024
Vendor
ClamAV
Product
Cisco ASR 5000 Series Software
Classifications
CWE-863, T1210
Attack vector
network
Privileges
admin

Timeline

How it unfolded

  1. Jun 4, 2021CVE publishedPublication date reported by the CVE source.
  2. Nov 7, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

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 privilegesadmin

What is affected?

ClamAV · Cisco ASR 5000 Series Softwareversion=n/a

Published CVSS scores

6.0NVDAV:N/AC:M/Au:S/C:P/I:P/A:P
8.1Cisco Systems, Inc. CNACVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H
7.2NVDCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
6.5Cisco Security AdvisoryCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/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
Privilegesadmin
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-863Incorrect Authorization
T1210Exploitation of Remote Services

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

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo