CVE-2026-91920
Undertow: undertow: chunkreader message length permits chunk-size overflow
- State
- Published
- Severity
- 6.5 Medium
- Published
- Oct 30, 2026
- Updated
- Oct 30, 2026
- Reserved
- Sep 15, 2026
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.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 3.1 | 6.5 Medium | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L | redhat |
Weaknesses
- CWE-444 Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')
Affected Products
| Product | Versions |
|---|---|
Red Hat build of Apache Camel for Spring Boot 4Red Hat | |
Red Hat Enterprise Linux 8Red Hat | |
Red Hat Enterprise Linux 8Red Hat | |
Red Hat Enterprise Linux 9Red Hat | |
Red Hat Fuse 7Red Hat | |
Red Hat JBoss Enterprise Application Platform 7Red Hat | |
Red Hat JBoss Enterprise Application Platform 7Red Hat | |
Red Hat JBoss Enterprise Application Platform 7Red Hat | |
Red Hat JBoss Enterprise Application Platform 7Red Hat | |
Red Hat JBoss Enterprise Application Platform 8Red Hat | |
Red Hat JBoss Enterprise Application Platform Expansion PackRed Hat | |
Red Hat Single Sign-On 7Red Hat |
References
- https://access.redhat.com/security/cve/CVE-2026-91920vdb-entry
- RHBZ#2528758issue-tracking
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