High [CVE-2026-28367] Undertow: undertow: request smuggling via `\r\r\r` as a header block terminator
This high-severity Red Hat Linux advisory covers CVE-2026-28367 affecting Red Hat JBoss Enterprise Application Platform 8.1.7.GA, Red Hat JBoss Enterprise Application Platform 8.1 for RHEL 8, Red Hat JBoss Enterprise Application Platform 8.1 for RHEL 9.
Aggregated and source-linked by VulniPulse. Data sources, validation and limitations.
VulniPulse record published
Android app · Google Play
Monitor future Red Hat Linux CVEs from your phone.
Choose a whole vendor or a precise platform, then receive matching security advisories by phone notification, email, or both. Coverage follows 34 official vendor sources and 160+ reviewed platform categories.
Summary
A flaw was found in Undertow. A remote attacker can exploit this vulnerability by sending `\r\r\r` as a header block terminator.
This can be used for request smuggling with certain proxy servers, such as older versions of Apache Traffic Server and Google Cloud Classic Application Load Balancer, potentially leading to unauthorized access or manipulation of web requests.
The Undertow web server is susceptible to request smuggling when deployed with certain proxy servers that forward `\r\r\r` as a header block terminator.
Red Hat products using Undertow in environments with vulnerable proxy configurations, such as those found in older versions of Apache Traffic Server or Google Cloud Classic Application Load Balancer, are at risk. Red Hat severity: Important — CVSS 8.7 (CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:N).
Weakness: CWE-444.
Affected Red Hat products: Red Hat JBoss Enterprise Application Platform 8.1.7.GA; Red Hat JBoss Enterprise Application Platform 8.1 for RHEL 8; Red Hat JBoss Enterprise Application Platform 8.1 for RHEL 9; Red Hat build of Apache Camel for Spring Boot 4; Red Hat Data Grid 8; Red Hat Fuse 7; Red Hat JBoss Enterprise Application Platform 7; Red Hat JBoss Enterprise Application Platform 8; Red Hat JBoss Enterprise Application Platform Expansion Pack; Red Hat Process Automation 7; Red Hat Single Sign-On 7.
Affected versions
No affected-version range was extracted from the source record. The vendor advisory is authoritative — check it before change work.
Official advisory · high-confidence parse· fetched 20 days ago·verify at source
- io.undertow/undertow-core:2.3.24.SP3-redhat-00001
- eap8-activemq-artemis-0:2.40.0-7.redhat_00015.1.el8eap
- eap8-eap-product-conf-parent-0:801.6.1-1.GA_redhat_00001.1.el8eap
- eap8-undertow-0:2.3.24-3.SP2_redhat_00001.1.el8eap
- eap8-wildfly-0:8.1.6-7.GA_redhat_00010.1.el8eap
- eap8-activemq-artemis-0:2.40.0-7.redhat_00015.1.el9eap
- eap8-eap-product-conf-parent-0:801.6.1-1.GA_redhat_00001.1.el9eap
- eap8-undertow-0:2.3.24-3.SP2_redhat_00001.1.el9eap
- eap8-wildfly-0:8.1.6-7.GA_redhat_00010.1.el9eap
- RHSA-2026:25126
- RHSA-2026:25125
Official advisory · high-confidence parse· fetched 20 days ago·verify at source
Mitigation checklist
- To mitigate this vulnerability, configure any proxy servers positioned in front of Undertow to strictly validate HTTP header terminations. Ensure that these proxies are configured to reject or normalize non-standard header block terminators, such as `\r\r\r`, before forwarding requests to Undertow. This operational control helps prevent request smuggling attacks by ensuring that only properly formed HTTP requests reach the Undertow server.
Official advisory · high-confidence parse· fetched 20 days ago·verify at source
Discussion(0)
No comments yet. Share field notes, upgrade gotchas, or questions — verify against the vendor advisory before acting on community advice.
Sign in to join the discussion.