# CVE-2026-28368: Undertow: undertow: request smuggling via inconsistent header parsing

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

A flaw was found in Undertow. This vulnerability allows a remote attacker to construct specially crafted requests where header names are parsed differently by Undertow compared to upstream proxies. This discrepancy in header interpretation can be exploited to launch request smuggling attacks, potentially bypassing security controls and accessing unauthorized resources.

## Remediation

- workaround: Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability. (source: CNA: redhat)

## 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: 0.73% as of 2026-11-04; percentile 54.42%

- 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-2026-28368 (CNA: redhat; vdb-entry, x_refsource_REDHAT)

- https://bugzilla.redhat.com/show_bug.cgi?id=2443261 (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-2026-28368 (secalert@redhat.com; Vendor Advisory)

- https://bugzilla.redhat.com/show_bug.cgi?id=2443261 (secalert@redhat.com; Issue Tracking, Vendor Advisory)

## Provenance

- CNA: redhat: https://www.cve.org/CVERecord?id=CVE-2026-28368; retrieved 2026-11-04; source updated 2026-11-04

- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-28368; retrieved 2026-11-05; source updated 2026-11-04

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-28368; retrieved 2026-11-04; source updated Not reported

Revision: d0eb05e7304f167849cd71af7197fc4cd05658b7370f1b967fead023216e6b5a

Canonical: https://y2.dev/cve/CVE-2026-28368

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