CVE-2021-40121Network attack vector

Script execution via unvalidated management-page input

Published Oct 21, 2021 · Updated Nov 7, 2024

Cross-site scripting in Cisco Identity Services Engine allows remote authenticated users to execute script in the web management interface. Specific management pages accept administrator-supplied code without properly validating it and later render the injected payload in another user's browser. Administrative credentials and a victim's interaction with an affected page are required; execution is limited to the interface's browser context and can expose browser-based information.

CVSS severity4.8
Medium
EPSS probability0.46%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Cross-site scripting in Cisco Identity Services Engine allows remote authenticated users to execute script in the web management interface. Specific management pages accept administrator-supplied code without properly validating it and later render the injected payload in another user's browser. Administrative credentials and a victim's interaction with an affected page are required; execution is limited to the interface's browser context and can expose browser-based information.

The record

CVE
CVE-2021-40121
Published
Oct 21, 2021
Updated
Nov 7, 2024
Vendor
ClamAV
Product
Cisco Identity Services Engine
Classifications
CWE-79, T1059.007
Attack vector
network
Privileges
admin

Timeline

How it unfolded

  1. Oct 21, 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 vectornetwork
Required privilegesadmin

What is affected?

ClamAV · Cisco Identity Services Engineversion=n/a

Published CVSS scores

4.8Cisco Security AdvisoryCVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:N
3.5NIST NVDAV:N/AC:M/Au:S/C:N/I:P/A:N
4.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:N

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
Privilegesadmin
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1059.007Command and Scripting Interpreter: JavaScript/JScript

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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