CVE-2026-91920
Full vulnerability record from the local CVENow database.
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.
Severity
MEDIUM
CVSS score
6.5
(v3.1)
Vulnerability status
Awaiting Analysis
Source identifier
Published
2026-10-30 02:17:10.140000
Last modified
2026-10-30 02:17:10.267000
View original CVE JSON
{
"id": "CVE-2026-91920",
"sourceIdentifier": "[email protected]",
"published": "2026-10-30T02:17:10.140",
"lastModified": "2026-10-30T02:17:10.267",
"vulnStatus": "Awaiting Analysis",
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "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."
}
],
"affected": [
{
"source": "[email protected]",
"affectedData": [
{
"vendor": "Red Hat",
"product": "Red Hat build of Apache Camel for Spring Boot 4",
"defaultStatus": "affected",
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"packageName": "undertow-servlet",
"cpes": [
"cpe:/a:redhat:camel_spring_boot:4"
]
},
{
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"packageName": "pki-core:10.6/resteasy",
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]
},
{
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"packageName": "pki-deps:10.6/resteasy",
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},
{
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]
},
{
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},
{
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"packageName": "jboss-eap-7/eap74-els-openjdk11-openshift-rhel8",
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},
{
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{
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},
{
"vendor": "Red Hat",
"product": "Red Hat JBoss Enterprise Application Platform Expansion Pack",
"defaultStatus": "unaffected",
"collectionURL": "https://access.redhat.com/jbossnetwork/restricted/listSoftware.html",
"packageName": "undertow-servlet",
"cpes": [
"cpe:/a:redhat:jbosseapxp"
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},
{
"vendor": "Red Hat",
"product": "Red Hat Single Sign-On 7",
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]
}
]
}
],
"metrics": {
"cvssMetricV31": [
{
"source": "[email protected]",
"type": "Primary",
"cvssData": {
"version": "3.1",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L",
"baseScore": 6.5,
"baseSeverity": "MEDIUM",
"attackVector": "NETWORK",
"attackComplexity": "LOW",
"privilegesRequired": "NONE",
"userInteraction": "NONE",
"scope": "UNCHANGED",
"confidentialityImpact": "NONE",
"integrityImpact": "LOW",
"availabilityImpact": "LOW"
},
"exploitabilityScore": 3.9,
"impactScore": 2.5
}
]
},
"weaknesses": [
{
"source": "[email protected]",
"type": "Primary",
"description": [
{
"lang": "en",
"value": "CWE-444"
}
]
}
],
"references": [
{
"url": "https://access.redhat.com/security/cve/CVE-2026-91920",
"source": "[email protected]"
},
{
"url": "https://bugzilla.redhat.com/show_bug.cgi?id=2528758",
"source": "[email protected]"
}
]
}