# CVE-2026-28369: Undertow: undertow: request smuggling via malformed http request headers

Status: published. Published: 2026-03-27. Updated: 2026-11-04.

A flaw was found in Undertow. When Undertow receives an HTTP request where the first header line starts with one or more spaces, it incorrectly processes the request by stripping these leading spaces. This behavior, which violates HTTP standards, can be exploited by a remote attacker to perform request smuggling. Request smuggling allows an attacker to bypass security mechanisms, access restricted information, or manipulate web caches, potentially leading to unauthorized actions or data exposure.

## Remediation

No remediation reported in collected sources

## Affected products and versions

- Red Hat / Red Hat JBoss Enterprise Application Platform 8.1.6 (io.undertow/undertow-core): ≥ 2.3.24.SP2-redhat-00001; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat JBoss Enterprise Application Platform 8.1 for RHEL 8 (eap8-activemq-artemis): ≥ 0:2.40.0-7.redhat_00015.1.el8eap; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat JBoss Enterprise Application Platform 8.1 for RHEL 8 (eap8-eap-product-conf-parent): ≥ 0:801.6.1-1.GA_redhat_00001.1.el8eap; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat JBoss Enterprise Application Platform 8.1 for RHEL 8 (eap8-undertow): ≥ 0:2.3.24-3.SP2_redhat_00001.1.el8eap; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat JBoss Enterprise Application Platform 8.1 for RHEL 8 (eap8-wildfly): ≥ 0:8.1.6-7.GA_redhat_00010.1.el8eap; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat JBoss Enterprise Application Platform 8.1 for RHEL 9 (eap8-activemq-artemis): ≥ 0:2.40.0-7.redhat_00015.1.el9eap; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat JBoss Enterprise Application Platform 8.1 for RHEL 9 (eap8-eap-product-conf-parent): ≥ 0:801.6.1-1.GA_redhat_00001.1.el9eap; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat JBoss Enterprise Application Platform 8.1 for RHEL 9 (eap8-undertow): ≥ 0:2.3.24-3.SP2_redhat_00001.1.el9eap; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat JBoss Enterprise Application Platform 8.1 for RHEL 9 (eap8-wildfly): ≥ 0:8.1.6-7.GA_redhat_00010.1.el9eap; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat build of Apache Camel for Spring Boot 4 (undertow-core): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat build of Apache Camel - HawtIO 4 (undertow-core): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Data Grid 8 (undertow-core): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 10 (moditect): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 8 (pki-core:10.6/resteasy): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 8 (pki-deps:10.6/resteasy): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 9 (resteasy): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Fuse 7 (undertow-core): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat JBoss Enterprise Application Platform 7 (undertow-core): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat JBoss Enterprise Application Platform 8 (org.jberet-jberet-parent): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat JBoss Enterprise Application Platform 8 (undertow-core): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat JBoss Enterprise Application Platform Expansion Pack (org.jberet-jberet-parent): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat JBoss Enterprise Application Platform Expansion Pack (org.jboss.eap-jboss-eap-xp): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat JBoss Enterprise Application Platform Expansion Pack (undertow-core): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Process Automation 7 (undertow-core): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Single Sign-On 7 (undertow-core): Version range not reported. Source: CNA: redhat

## NVD configuration conditions

Affected CPE matches depend on the following AND/OR and negation conditions:

```json
[
  {
    "negate": false,
    "nodes": [
      {
        "cpeMatch": [
          {
            "criteria": "cpe:2.3:a:redhat:build_of_apache_camel_-_hawtio:4.0:*:*:*:*:*:*:*",
            "vulnerable": true
          },
          {
            "criteria": "cpe:2.3:a:redhat:build_of_apache_camel_for_spring_boot:4.0:*:*:*:*:*:*:*",
            "vulnerable": true
          },
          {
            "criteria": "cpe:2.3:a:redhat:data_grid:8.0:*:*:*:*:*:*:*",
            "vulnerable": true
          },
          {
            "criteria": "cpe:2.3:a:redhat:fuse:7.0.0:*:*:*:*:*:*:*",
            "vulnerable": true
          },
          {
            "criteria": "cpe:2.3:a:redhat:jboss_enterprise_application_platform:7.0.0:*:*:*:*:*:*:*",
            "vulnerable": true
          },
          {
            "criteria": "cpe:2.3:a:redhat:jboss_enterprise_application_platform:8.0.0:*:*:*:*:*:*:*",
            "vulnerable": true
          },
          {
            "criteria": "cpe:2.3:a:redhat:jboss_enterprise_application_platform_expansion_pack:-:*:*:*:*:*:*:*",
            "vulnerable": true
          },
          {
            "criteria": "cpe:2.3:a:redhat:process_automation:7.0:*:*:*:*:*:*:*",
            "vulnerable": true
          },
          {
            "criteria": "cpe:2.3:a:redhat:single_sign-on:7.0:*:*:*:*:*:*:*",
            "vulnerable": true
          },
          {
            "criteria": "cpe:2.3:a:redhat:undertow:-:*:*:*:*:*:*:*",
            "vulnerable": true
          },
          {
            "criteria": "cpe:2.3:o:redhat:enterprise_linux:9.0:*:*:*:*:*:*:*",
            "vulnerable": true
          }
        ],
        "negate": false,
        "operator": "OR"
      }
    ],
    "operator": "OR"
  }
]
```

## Severity and prioritization

- CVSS 3.1: 8.7 (high); CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:N; source: CNA: redhat

- CVSS 3.1: 9.1 (critical); CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N; source: NVD: nvd@nist.gov

- CVSS 3.1: 8.7 (high); CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:N; source: NVD: secalert@redhat.com

- CISA KEV: No listing in collected sources

- EPSS: 0.69% as of 2026-11-04; percentile 52.87%

- SSVC: exploitation none; automatable no; technical impact total; source ADP: CISA-ADP

- Weaknesses: CWE-444

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://access.redhat.com/errata/RHSA-2026:25125 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:25126 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/security/cve/CVE-2026-28369 (CNA: redhat; vdb-entry, x_refsource_REDHAT)

- https://bugzilla.redhat.com/show_bug.cgi?id=2443262 (CNA: redhat; issue-tracking, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:25125 (secalert@redhat.com)

- https://access.redhat.com/errata/RHSA-2026:25126 (secalert@redhat.com)

- https://access.redhat.com/security/cve/CVE-2026-28369 (secalert@redhat.com; Vendor Advisory)

- https://bugzilla.redhat.com/show_bug.cgi?id=2443262 (secalert@redhat.com; Issue Tracking, Vendor Advisory)

## Provenance

- CNA: redhat: https://www.cve.org/CVERecord?id=CVE-2026-28369; retrieved 2026-11-04; source updated 2026-11-04

- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-28369; retrieved 2026-11-05; source updated 2026-11-04

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-28369; retrieved 2026-11-04; source updated Not reported

Revision: 44ca4dac0796412f5ec1683bcf56c1c297f70524be3e5d2ecb4e91cd3aa17b0f

Canonical: https://y2.dev/cve/CVE-2026-28369

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