EUVD-2026-16698
GHSA-vqqj-9cmv-hx43
CVSS Vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:N
Lifecycle Timeline
3Description
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.
Analysis
Undertow's improper handling of HTTP requests with leading whitespace in header lines enables remote, unauthenticated request smuggling attacks (CWE-444) against Red Hat middleware and enterprise products. Attackers can exploit this HTTP standard violation to bypass security controls, access restricted data, or poison web caches across a wide deployment base including JBoss EAP 7/8, Red Hat Fuse 7, Data Grid 8, and RHEL 8/9/10 distributions. …
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Remediation
Within 24 hours: Inventory all JBoss EAP 7.x, 8.x, Red Hat Fuse 7.x, Data Grid 8.x, and RHEL 8/9/10 systems; enable detailed HTTP request logging and monitor for malformed headers with leading whitespace. Within 7 days: Deploy WAF rules to reject HTTP requests with leading whitespace in header lines; segment affected middleware from untrusted networks where feasible; consult Red Hat Security Advisories for Undertow-specific guidance. …
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