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.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- None
- Integrity
- Low
- Availability
- Low
Exploit likelihood
What each source reports
CVE List Score used
6.5
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.
- Record
CVE-2026-91920- CVSS 3.1
- 6.5 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L - Weakness
- CWE-444
- Updated
- 2026-11-06
EUVDEUVD-2026-113473
6.5
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.
- Record
EUVD-2026-113473- CVSS 3.1
- 6.5 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L - Updated
- 2026-11-06
GitHub AdvisoriesGHSA-3f65-g3hr-c59r
6.5
A flaw was found in the ChunkReader component of the Undertow web server, which is used to handle...
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.
- Record
GHSA-3f65-g3hr-c59r- CVSS 3.1
- 6.5 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L - Weakness
- CWE-444
- Updated
- 2026-11-02
NVD
6.5
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.
- Record
CVE-2026-91920- CVSS 3.1
- 6.5 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L - Weakness
- CWE-444
- Updated
- 2026-11-06
OSVDEBIAN-CVE-2026-91920
6.5
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.
- Record
DEBIAN-CVE-2026-91920- CVSS 3.1
- 6.5 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L - Updated
- 2026-11-04
OSVUBUNTU-CVE-2026-91920
6.5
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.
- Record
UBUNTU-CVE-2026-91920- CVSS 3.1
- 6.5 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L - Updated
- 2026-11-05
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
undertowDebian:14 |
All versions, plus listed versions 1.3.11-11.3.16-11.3.19-11.3.21-11.3.23-1 Show 45 moreShow less1.3.4-11.3.5-11.3.7-11.4.0-11.4.1-11.4.18-11.4.20-11.4.21-11.4.21-21.4.22-11.4.23-11.4.23-21.4.23-31.4.25-11.4.25-21.4.3-11.4.4-11.4.6-11.4.7-11.4.8-12.0.23-12.0.25-12.0.26-12.0.27-12.0.28-12.0.29-12.0.30-12.1.0-12.1.1-12.1.3-12.2.0-12.2.10-12.2.12-12.2.13-12.2.14-12.2.16-12.2.17-12.2.18-12.2.19-12.2.2-12.2.20-12.2.21-12.2.3-12.2.4-12.2.5-1 |
None known |
undertowUbuntu:Pro:16.04:LTS |
All versions, plus listed versions 1.3.4-11.3.5-11.3.7-11.3.11-11.3.16-11.3.16-1ubuntu0.1~esm1 |
None known |
undertowUbuntu:Pro:18.04:LTS |
All versions, plus listed versions 1.4.20-11.4.21-11.4.22-11.4.23-11.4.23-2build11.4.23-31.4.23-3ubuntu0.1~esm1 |
None known |
undertowUbuntu:Pro:20.04:LTS |
All versions, plus listed versions 2.0.23-12.0.27-12.0.28-12.0.29-12.0.29-1ubuntu0.1~esm1 |
None known |
undertowUbuntu:Pro:22.04:LTS |
All versions, plus listed versions 2.2.8-12.2.12-12.2.13-12.2.14-12.2.16-12.2.16-1ubuntu0.1~esm1 |
None known |
undertowUbuntu:Pro:24.04:LTS |
All versions, plus listed versions 2.3.8-22.3.8-2ubuntu0.1~esm1 |
None known |
undertowUbuntu:26.10 |
All versions, plus listed versions 2.3.20-1ubuntu1 |
None known |
undertowUbuntu:26.04:LTS |
All versions, plus listed versions 2.3.18-22.3.20-12.3.20-1ubuntu1 |
None known |
History
| Recorded | Changed | Sources |
|---|---|---|
| published | EUVD, NVD, OSV | |
| facts | CVE List, EUVD, NVD, OSV | |
| first indexed | CVE List, EUVD, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2026-91920 is a medium vulnerability (CVSS 6.5) in Red Hat Build Of Apache Camel For Spring Boot 4, published October 30, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.24%, the 14th percentile. No source names a fixed version.
References
Left out here: 6 versions. The JSON record has them.