CVE-2021-40336Network attack vector

Browser content injection via unvalidated HTTP header

Published Jul 25, 2022 · Updated Sep 17, 2024

HTTP response splitting in Hitachi Energy Modular Switchgear Monitoring 2.2 and earlier allows attackers to inject browser content. The web interface places unvalidated HTTP header data into a response, allowing crafted CRLF sequences to split the response and introduce attacker-controlled content. Exploitation requires an MSM user with an established session to follow a forged link, exposing session cookies or delivering malicious software.

CVSS severity8.8
High
EPSS probability0.47%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

HTTP response splitting in Hitachi Energy Modular Switchgear Monitoring 2.2 and earlier allows attackers to inject browser content. The web interface places unvalidated HTTP header data into a response, allowing crafted CRLF sequences to split the response and introduce attacker-controlled content. Exploitation requires an MSM user with an established session to follow a forged link, exposing session cookies or delivering malicious software.

The record

CVE
CVE-2021-40336
Published
Jul 25, 2022
Updated
Sep 17, 2024
Vendor
Hitachi Energy
Product
Modular Switchgear Monitoring
Classifications
CWE-113, CWE-74, T1189
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 25, 2022CVE publishedPublication date reported by the CVE source.
  2. Sep 17, 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=v2.2 <=V2.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Hitachi Energy · Modular Switchgear Monitoringversion=v2.2 <=V2.2

Published CVSS scores

8.8NISTCVSS:3.1/AV:N/AC:L/PR:N/UI:R/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.

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-113Improper Neutralization of CRLF Sequences in HTTP Headers ('HTTP Request/Response Splitting')
CWE-74Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')
T1189Drive-by Compromise

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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