CVE-2026-91920
Undertow: undertow: chunkreader message length permits chunk-size overflow
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.
Fixes and workarounds
No remediation reported in collected sources.
Missing remediation information is not evidence that no patch exists.
Affected products and versions
| Product | Versions | Authority |
|---|---|---|
| Red Hat build of Apache Camel for Spring Boot 4 Red Hat undertow-servlet
https://access.redhat.com/downloads/content/package-browser/ |
Range not reported
Other versions: affected |
CNA: redhat |
| Red Hat Enterprise Linux 8 Red Hat pki-core:10.6/resteasy
https://access.redhat.com/downloads/content/package-browser/ |
Range not reported
Other versions: unknown |
CNA: redhat |
| Red Hat Enterprise Linux 8 Red Hat pki-deps:10.6/resteasy
https://access.redhat.com/downloads/content/package-browser/ |
Range not reported
Other versions: unknown |
CNA: redhat |
| Red Hat Enterprise Linux 9 Red Hat resteasy
https://access.redhat.com/downloads/content/package-browser/ |
Range not reported
Other versions: unknown |
CNA: redhat |
| Red Hat Fuse 7 Red Hat undertow-servlet
https://access.redhat.com/downloads/content/package-browser/ |
Range not reported
Other versions: affected |
CNA: redhat |
| Red Hat JBoss Enterprise Application Platform 7 Red Hat jboss-eap-7/eap74-els-openjdk11-openshift-rhel8
https://access.redhat.com/jbossnetwork/restricted/listSoftware.html |
Range not reported
Other versions: affected |
CNA: redhat |
| Red Hat JBoss Enterprise Application Platform 7 Red Hat jboss-eap-7/eap74-els-openjdk17-openshift-rhel8
https://access.redhat.com/jbossnetwork/restricted/listSoftware.html |
Range not reported
Other versions: affected |
CNA: redhat |
| Red Hat JBoss Enterprise Application Platform 7 Red Hat jboss-eap-7/eap74-els-openjdk8-openshift-rhel8
https://access.redhat.com/jbossnetwork/restricted/listSoftware.html |
Range not reported
Other versions: affected |
CNA: redhat |
| Red Hat JBoss Enterprise Application Platform 7 Red Hat undertow-servlet
https://access.redhat.com/jbossnetwork/restricted/listSoftware.html |
Range not reported
Other versions: affected |
CNA: redhat |
| Red Hat JBoss Enterprise Application Platform 8 Red Hat undertow-servlet
https://access.redhat.com/jbossnetwork/restricted/listSoftware.html |
Range not reported
Other versions: affected |
CNA: redhat |
| Red Hat JBoss Enterprise Application Platform Expansion Pack Red Hat undertow-servlet
https://access.redhat.com/jbossnetwork/restricted/listSoftware.html |
Range not reported
Other versions: unaffected |
CNA: redhat |
| Red Hat Single Sign-On 7 Red Hat undertow-servlet
https://access.redhat.com/downloads/content/package-browser/ |
Range not reported
Other versions: affected |
CNA: redhat |
Version ranges are source assertions. Check the vendor advisory and your installed configuration before determining exposure.
CVSS assessments
| Version / score | Vector | Authority |
|---|---|---|
| 3.1 / 6.5 medium |
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L | CNA: redhat |
Exploit evidence
No exploit evidence in collected sources. This is not proof of no exploitation.
References
- https://access.redhat.com/security/cve/CVE-2026-91920CNA: redhat · vdb-entry, x_refsource_REDHAT
- https://bugzilla.redhat.com/show_bug.cgi?id=2528758CNA: redhat · issue-tracking, x_refsource_REDHAT
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