CVE-2023-34037Network attack vector

Integrity impact via HTTP request smuggling

Published Aug 4, 2023 · Updated Oct 21, 2024

HTTP request smuggling in VMware Horizon Server through 2306 allows remote attackers to perform smuggled requests via crafted HTTP. The connection-server HTTP parser inconsistently interprets request boundaries, allowing an attacker with network access to desynchronize front-end and back-end request handling. Exploitation requires network reachability to the Horizon service and can alter the integrity of requests processed by the server; the public record does not establish confidentiality or availability impact.

CVSS severity5.3
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

HTTP request smuggling in VMware Horizon Server through 2306 allows remote attackers to perform smuggled requests via crafted HTTP. The connection-server HTTP parser inconsistently interprets request boundaries, allowing an attacker with network access to desynchronize front-end and back-end request handling. Exploitation requires network reachability to the Horizon service and can alter the integrity of requests processed by the server; the public record does not establish confidentiality or availability impact.

The record

CVE
CVE-2023-34037
Published
Aug 4, 2023
Updated
Oct 21, 2024
Vendor
VMware
Product
VMware Horizon Server
Classifications
CWE-444, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 4, 2023CVE publishedPublication date reported by the CVE source.
  2. Oct 21, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=Horizon Server 2306, Horizon Server 2303, Horizon Server 2212, Horizon Server 2209, Horizon Server 2206, Horizon Server 2111.x, Horizon Server 2106, Horizon Server 2103, Horizon Server 2012, Horizon Server 2006

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

VMware · VMware Horizon Serverversion=Horizon Server 2306, Horizon Server 2303, Horizon Server 2212, Horizon Server 2209, Horizon Server 2206, Horizon Server 2111.x, Horizon Server 2106, Horizon Server 2103, Horizon Server 2012, Horizon Server 2006

Published CVSS scores

5.3VMware CNACVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/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-444Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')
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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