A flaw was found in the ChunkReader component of the Undertow web server, which is used to handle chunked transfer encoding in HTTP requests. The issue occurs because a security check for the chunk size is performed before the value is shifted, allowing a specifically crafted 15-digit chunk size to bypass the limit and overflow into internal state flags. This can cause the server to terminate a request body prematurely and interpret the remaining data as a separate, smuggled request.
History

Mon, 02 Nov 2026 22:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Fri, 30 Oct 2026 01:30:00 +0000

Type Values Removed Values Added
Title undertow: undertow: ChunkReader message length permits chunk-size overflow Undertow: undertow: chunkreader message length permits chunk-size overflow
First Time appeared Redhat
Redhat camel Spring Boot
Redhat enterprise Linux
Redhat jboss Enterprise Application Platform
Redhat jboss Fuse
Redhat jbosseapxp
Redhat red Hat Single Sign On
CPEs cpe:/a:redhat:camel_spring_boot:4
cpe:/a:redhat:jboss_enterprise_application_platform:7
cpe:/a:redhat:jboss_enterprise_application_platform:8
cpe:/a:redhat:jboss_fuse:7
cpe:/a:redhat:jbosseapxp
cpe:/a:redhat:red_hat_single_sign_on:7
cpe:/o:redhat:enterprise_linux:8
cpe:/o:redhat:enterprise_linux:9
Vendors & Products Redhat
Redhat camel Spring Boot
Redhat enterprise Linux
Redhat jboss Enterprise Application Platform
Redhat jboss Fuse
Redhat jbosseapxp
Redhat red Hat Single Sign On
References

Fri, 30 Oct 2026 00:30:00 +0000

Type Values Removed Values Added
Description A flaw was found in the ChunkReader component of the Undertow web server, which is used to handle chunked transfer encoding in HTTP requests. The issue occurs because a security check for the chunk size is performed before the value is shifted, allowing a specifically crafted 15-digit chunk size to bypass the limit and overflow into internal state flags. This can cause the server to terminate a request body prematurely and interpret the remaining data as a separate, smuggled request.
Title undertow: undertow: ChunkReader message length permits chunk-size overflow
Weaknesses CWE-444
References
Metrics threat_severity

None

cvssV3_1

{'score': 6.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L'}

threat_severity

Moderate


cve-icon MITRE

Status: PUBLISHED

Assigner: redhat

Published: 2026-10-30T01:16:53.416Z

Updated: 2026-11-02T21:28:39.310Z

Reserved: 2026-09-15T10:20:33.140Z

Link: CVE-2026-91920

cve-icon Vulnrichment

Updated: 2026-11-02T20:40:16.205Z

cve-icon NVD

Status : Awaiting Analysis

Published: 2026-10-30T02:17:10.140

Modified: 2026-11-02T21:17:40.403

Link: CVE-2026-91920

cve-icon Redhat

Severity : Moderate

Publid Date: 2026-10-29T12:11:57Z

Links: CVE-2026-91920 - Bugzilla