CVE-2026-28367Network attack vector

Request smuggling via nonstandard header termination

Published Mar 27, 2026 · Updated Mar 27, 2026

HTTP request smuggling in Red Hat Undertow 2.3.23.Final and earlier allows remote attackers to manipulate proxied web requests. Undertow treats three consecutive carriage returns as an HTTP header-block terminator, while certain forwarding proxies preserve that nonstandard sequence. Exploitation requires a proxy with different parsing behavior, enabling unauthorized access or request manipulation without interrupting the service.

CVSS severity8.7
High
EPSS probability0.71%
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 Red Hat Undertow 2.3.23.Final and earlier allows remote attackers to manipulate proxied web requests. Undertow treats three consecutive carriage returns as an HTTP header-block terminator, while certain forwarding proxies preserve that nonstandard sequence. Exploitation requires a proxy with different parsing behavior, enabling unauthorized access or request manipulation without interrupting the service.

The record

CVE
CVE-2026-28367
Published
Mar 27, 2026
Updated
Mar 27, 2026
Vendor
389 Directory Server
Product
Red Hat JBoss Enterprise Application Platform Expansion Pack
Classifications
CWE-444, CAPEC-33, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 27, 2026CVE publishedPublication date reported by the CVE source.
  2. Mar 27, 2026Record 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 versions are unavailable in this record. Check the vendor advisory for version and patch details.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

389 Directory Server · Red Hat JBoss Enterprise Application Platform Expansion PackAffected versions are unavailable in this record.
389 Directory Server · Red Hat build of Apache Camel for Spring BootAffected versions are unavailable in this record.
389 Directory Server · Red Hat Single Sign-On 7Affected versions are unavailable in this record.
389 Directory Server · Red Hat Fuse 7Affected versions are unavailable in this record.
389 Directory Server · Red Hat Process Automation Manager 7Affected versions are unavailable in this record.
389 Directory Server · Red Hat build of Apache Camel HawtIOAffected versions are unavailable in this record.
389 Directory Server · Red Hat Data GridAffected versions are unavailable in this record.
389 Directory Server · Red Hat JBoss Enterprise Application PlatformAffected versions are unavailable in this record.
389 Directory Server · Red Hat Enterprise Linux 8Affected versions are unavailable in this record.

Published CVSS scores

9.1NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
8.7Red HatCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/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')
CAPEC-33HTTP Request 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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