CVE-2021-34721

Root command execution via XML command validation

Published Sep 9, 2021 · Updated Nov 7, 2024

OS command injection in Cisco IOS XR Software before 7.3.2 allows local users to execute arbitrary commands as root through the XML agent. The XML configuration manager insufficiently validates user-supplied commands before passing them for execution on the underlying Linux system. Exploitation requires authenticated access to an affected device with the XML agent feature configured and grants a root shell with full command execution.

CVSS severity6.7
Medium
EPSS probability0.28%
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

OS command injection in Cisco IOS XR Software before 7.3.2 allows local users to execute arbitrary commands as root through the XML agent. The XML configuration manager insufficiently validates user-supplied commands before passing them for execution on the underlying Linux system. Exploitation requires authenticated access to an affected device with the XML agent feature configured and grants a root shell with full command execution.

The record

CVE
CVE-2021-34721
Published
Sep 9, 2021
Updated
Nov 7, 2024
Vendor
ClamAV
Product
Cisco IOS XR Software
Classifications
CWE-78, CAPEC-88, T1059.004
Attack vector
local
Privileges
admin

Timeline

How it unfolded

  1. Sep 9, 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 vectorlocal
Required privilegesadmin

What is affected?

ClamAV · Cisco IOS XR Softwareversion=n/a

Published CVSS scores

6.7Cisco Systems, Inc.CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
6.9NIST National Vulnerability DatabaseAV:L/AC:M/Au:N/C:C/I:C/A:C

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)
Vectorlocal
Privilegesadmin
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-78Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')
CAPEC-88OS Command Injection
T1059.004Command and Scripting Interpreter: Unix Shell

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