CVE-2026-91920medium6.5

Undertow: undertow: chunkreader message length permits chunk-size overflow

Impact

A flaw in Undertow's ChunkReader component allows a crafted 15-digit chunk size to bypass the limit and overflow, potentially causing the server to terminate a request body prematurely and interpret remaining data as a separate request. The issue affects Red Hat products, including Red Hat build of Apache Camel for Spring Boot 4 and Red Hat JBoss Enterprise Application Platform 7. The impact is related to HTTP Request Smuggling.

Summarized by @cf/meta/llama-3.3-70b-instruct-fp8-fast. Verify details against the original sources.

Affected packages

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Affected products

Vendor version evidence. Product records are separate from automatic dependency matching.

Red Hat · redhat

Red Hat build of Apache Camel for Spring Boot 4

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Other versions: affected

Product identifiers (CPE)

cpe:/a:redhat:camel_spring_boot:4

Red Hat · redhat

Red Hat Enterprise Linux 8

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Product identifiers (CPE)

cpe:/o:redhat:enterprise_linux:8

Red Hat · redhat

Red Hat Enterprise Linux 8

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Product identifiers (CPE)

cpe:/o:redhat:enterprise_linux:8

Red Hat · redhat

Red Hat Enterprise Linux 9

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Product identifiers (CPE)

cpe:/o:redhat:enterprise_linux:9

Red Hat · redhat

Red Hat Fuse 7

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Product identifiers (CPE)

cpe:/a:redhat:jboss_fuse:7

Red Hat · redhat

Red Hat JBoss Enterprise Application Platform 7

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Product identifiers (CPE)

cpe:/a:redhat:jboss_enterprise_application_platform:7

Red Hat · redhat

Red Hat JBoss Enterprise Application Platform 7

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Product identifiers (CPE)

cpe:/a:redhat:jboss_enterprise_application_platform:7

Red Hat · redhat

Red Hat JBoss Enterprise Application Platform 7

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Product identifiers (CPE)

cpe:/a:redhat:jboss_enterprise_application_platform:7

Red Hat · redhat

Red Hat JBoss Enterprise Application Platform 7

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Product identifiers (CPE)

cpe:/a:redhat:jboss_enterprise_application_platform:7

Red Hat · redhat

Red Hat JBoss Enterprise Application Platform 8

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Product identifiers (CPE)

cpe:/a:redhat:jboss_enterprise_application_platform:8

Red Hat · redhat

Red Hat JBoss Enterprise Application Platform Expansion Pack

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Other versions: unaffected

Product identifiers (CPE)

cpe:/a:redhat:jbosseapxp

Red Hat · redhat

Red Hat Single Sign-On 7

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Product identifiers (CPE)

cpe:/a:redhat:red_hat_single_sign_on:7

Original source 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.

Inside the record

Evidence available

Package identity · not supplied

Version evidence · not supplied

Remediation guidance · not supplied

Weakness classification

Additional publishers · not supplied

Describes the evidence in this view, not whether the product is safe.

Original records

CVE-2026-91920

View the latest unmodified CVE JSON from the official source. It may be newer than this imported page.

cve.new JSON →

Underlying weaknesses

The source’s classification of what caused the vulnerability.

CWE-444 ↗

Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')

redhat

Contributing organizations · 1

redhat

Assigning organization

2026-10-30

What changed

Follow changes

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Large field values are marked as truncated previews. Original source snapshots remain retained.

References

2 sources

access.redhat.com/security/cve/CVE-2026-91920

vdb-entryredhat

bugzilla.redhat.com/show_bug.cgi

issue-trackingredhat

Priority and evidence

Not in CISA KEVNo package fix recorded

KEV coverage does not rule out exploitation.

KEV checked 31/10/2026, 09:10:30 UTC

redhat · CVSS:3.1 · 6.5

Assessment vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L

Reading the signals

Severity · CVSS: Technical impact and attack conditions. The headline is the highest imported catalog score; sources may disagree.
Observed exploitation · KEV: An absent or unavailable KEV listing does not establish that exploitation has not occurred.
Predicted exploitation · EPSS: No EPSS estimate available in this record.

Record details

Published: 30/10/2026, 01:16:53 UTC
Modified: 30/10/2026, 01:16:53 UTC
Last imported by cve.new: 30/10/2026, 02:46:45 UTC
Aliases: None recorded

Source evidence

Request a correction or dispute

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Find the responsible CNA →Official dispute and escalation process ↗

CVE CVE-2026-91920

Enrichment coverage

NVDAvailable

Checked 30/10/2026, 03:05:34 UTC

GHSANo result

Checked 30/10/2026, 03:05:34 UTC

EUVDAvailable

Checked 30/10/2026, 03:05:36 UTC

EPSSNo result

Checked 30/10/2026, 03:05:33 UTC

Additional source evidence

NVD · CVE-2026-91920

CVSS 6.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L

Checked 30/10/2026, 03:05:34 UTC

ENISA EUVD · EUVD-2026-113473

CVSS 6.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L

Checked 30/10/2026, 03:05:36 UTC

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