CVE-2023-38709Network attack vector

Response splitting via unvalidated backend Content-Type

Published Apr 4, 2024 · Updated Nov 4, 2025

HTTP response splitting in Apache HTTP Server 2.4.58 and earlier allows remote attackers to alter responses via crafted backend headers. Core response processing accepts application-controlled Content-Type values without rejecting embedded response delimiters, causing one response to be parsed as multiple responses. Exploitation requires a malicious or exploitable hosted or proxied content generator, and the resulting split can alter data delivered to downstream clients.

CVSS severity7.3
High
EPSS probability3.91%
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 Apache HTTP Server 2.4.58 and earlier allows remote attackers to alter responses via crafted backend headers. Core response processing accepts application-controlled Content-Type values without rejecting embedded response delimiters, causing one response to be parsed as multiple responses. Exploitation requires a malicious or exploitable hosted or proxied content generator, and the resulting split can alter data delivered to downstream clients.

The record

CVE
CVE-2023-38709
Published
Apr 4, 2024
Updated
Nov 4, 2025
Vendor
The Apache Software Foundation
Product
Apache HTTP Server
Classifications
CWE-1284, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 4, 2024CVE publishedPublication date reported by the CVE source.
  2. Nov 4, 2025Record 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=0 <=2.4.58

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Apache Software Foundation · Apache HTTP Serverversion=0 <=2.4.58

Published CVSS scores

7.3CISA ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L

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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-1284Improper Validation of Specified Quantity in Input
T1190Exploit Public-Facing Application

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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