CVE-2021-34728

Authenticated privilege escalation via insufficient CLI validation

Published Sep 9, 2021 · Updated Nov 7, 2024

Privilege escalation in Cisco IOS XR Software before releases 7.3.2 and 7.4.1 allows remote authenticated users with low-privileged accounts to gain root through crafted CLI commands. The CLI insufficiently validates command input supplied by the user, allowing crafted commands at the prompt to bypass privilege boundaries. Exploitation requires local access to an affected device and an authenticated low-privileged account; successful exploitation grants root privileges with confidentiality, integrity, and availability impact.

CVSS severity7.8
High
EPSS probability0.30%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Privilege escalation in Cisco IOS XR Software before releases 7.3.2 and 7.4.1 allows remote authenticated users with low-privileged accounts to gain root through crafted CLI commands. The CLI insufficiently validates command input supplied by the user, allowing crafted commands at the prompt to bypass privilege boundaries. Exploitation requires local access to an affected device and an authenticated low-privileged account; successful exploitation grants root privileges with confidentiality, integrity, and availability impact.

The record

CVE
CVE-2021-34728
Published
Sep 9, 2021
Updated
Nov 7, 2024
Vendor
ClamAV
Product
Cisco IOS XR Software
Classifications
CWE-78, T1068
Attack vector
local
Privileges
authenticated

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

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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 vectorlocal
Required privilegesauthenticated

What is affected?

ClamAV · Cisco IOS XR Softwareversion=n/a

Published CVSS scores

7.8Cisco Systems, Inc.CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/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)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-78Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')
T1068Exploitation for Privilege Escalation

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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