CVE-2021-22811Network attack vector

Privileged-session script execution via intercepted request

Published Jan 28, 2022 · Updated Aug 3, 2024

Cross-site scripting in Schneider Electric NMC2 and NMC3 firmware allows man-in-the-middle attackers to execute script in a privileged session. Interception of a privileged account's request to a vulnerable management page causes script execution, but the affected endpoint and exact input-handling error are undisclosed. Exploitation requires the privileged user to access that page while the request is intercepted; the script then runs in that user's browser context.

CVSS severity6.8
Medium
EPSS probability0.74%
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 Schneider Electric NMC2 and NMC3 firmware allows man-in-the-middle attackers to execute script in a privileged session. Interception of a privileged account's request to a vulnerable management page causes script execution, but the affected endpoint and exact input-handling error are undisclosed. Exploitation requires the privileged user to access that page while the request is intercepted; the script then runs in that user's browser context.

The record

CVE
CVE-2021-22811
Published
Jan 28, 2022
Updated
Aug 3, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-79
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 28, 2022CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 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?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

6.8Schneider ElectricCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N
6.1NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
4.3NIST NVDAV:N/AC:M/Au:N/C:N/I:P/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.

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
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

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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