CVE-2021-38944Network attack vector

Unauthenticated response header injection via Host line breaks

Published May 18, 2022 · Updated Sep 16, 2024

HTTP header injection in IBM DataPower Gateway allows remote attackers to inject response headers through crafted Host input. Host-header handling fails to reject line breaks before using the value in an HTTP response header, so a supplied break starts another header field. No authentication is required; injected headers can enable cross-site scripting, cache poisoning, or session hijacking.

CVSS severity4.8
Medium
EPSS probability0.58%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

HTTP header injection in IBM DataPower Gateway allows remote attackers to inject response headers through crafted Host input. Host-header handling fails to reject line breaks before using the value in an HTTP response header, so a supplied break starts another header field. No authentication is required; injected headers can enable cross-site scripting, cache poisoning, or session hijacking.

The record

CVE
CVE-2021-38944
Published
May 18, 2022
Updated
Sep 16, 2024
Vendor
IBM
Product
IBM DataPower Gateway
Classifications
CWE-79, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 18, 2022CVE publishedPublication date reported by the CVE source.
  2. Sep 16, 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=10.0.1.0
  2. Affected versionversion=10.0.1.5
  3. Affected versionversion=10.0.2.0
  4. Affected versionversion=10.0.3.0
  5. Affected versionversion=2018.4.1.0
  6. Affected versionversion=2018.4.1.18

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

IBM · IBM DataPower Gatewayversion=10.0.1.0; version=10.0.1.5; version=10.0.2.0; version=10.0.3.0; version=2018.4.1.0; version=2018.4.1.18

Published CVSS scores

4.8IBMCVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/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.

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')
T1190Exploit Public-Facing Application

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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