CVE-2026-33079
Full vulnerability record from the local CVENow database.
Description
In versions 3.0.0a1 through 3.2.0 of Mistune, there is a ReDoS (Regular Expression Denial of Service) vulnerability in `LINK_TITLE_RE` that allows an attacker who can supply Markdown for parsing to cause denial of service. The regular expression used for parsing link titles contains overlapping alternatives that can trigger catastrophic backtracking. In both the double-quoted and single-quoted branches, a backslash followed by punctuation can be matched either as an escaped punctuation sequence or as two ordinary characters, creating an ambiguous pattern inside a repeated group. If an attacker supplies Markdown containing repeated ! sequences with no closing quote, the regex engine explores an exponential number of backtracking paths. This is reachable through normal Markdown parsing of inline links and block link reference definitions. A small crafted input can therefore cause significant CPU consumption and make applications using Mistune unresponsive.
Severity
HIGH
CVSS score
8.7
(v4.0)
Vulnerability status
Deferred
Source identifier
Published
2026-05-06 18:16:03.097000
Last modified
2026-10-26 19:10:00.163000
View original CVE JSON
{
"id": "CVE-2026-33079",
"sourceIdentifier": "[email protected]",
"published": "2026-05-06T18:16:03.097",
"lastModified": "2026-10-26T19:10:00.163",
"vulnStatus": "Deferred",
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "In versions 3.0.0a1 through 3.2.0 of Mistune, there is a ReDoS (Regular Expression Denial of Service) vulnerability in `LINK_TITLE_RE` that allows an attacker who can supply Markdown for parsing to cause denial of service. The regular expression used for parsing link titles contains overlapping alternatives that can trigger catastrophic backtracking. In both the double-quoted and single-quoted branches, a backslash followed by punctuation can be matched either as an escaped punctuation sequence or as two ordinary characters, creating an ambiguous pattern inside a repeated group. If an attacker supplies Markdown containing repeated ! sequences with no closing quote, the regex engine explores an exponential number of backtracking paths. This is reachable through normal Markdown parsing of inline links and block link reference definitions. A small crafted input can therefore cause significant CPU consumption and make applications using Mistune unresponsive."
},
{
"lang": "es",
"value": "En las versiones 3.0.0a1 a 3.2.0 de Mistune, existe una vulnerabilidad ReDoS (denegación de servicio por expresión regular) en LINK_TITLE_RE que permite a un atacante que puede proporcionar Markdown para su análisis causar una denegación de servicio. La expresión regular utilizada para analizar títulos de enlaces contiene alternativas superpuestas que pueden desencadenar un retroceso catastrófico. Tanto en las ramas con comillas dobles como con comillas simples, una barra invertida seguida de puntuación puede coincidir como una secuencia de puntuación escapada o como dos caracteres ordinarios, creando un patrón ambiguo dentro de un grupo repetido. Si un atacante proporciona Markdown que contiene secuencias repetidas de ! sin comilla de cierre, el motor de expresiones regulares explora un número exponencial de rutas de retroceso. Esto es alcanzable a través del análisis normal de Markdown de enlaces en línea y definiciones de referencia de enlaces de bloque. Una pequeña entrada manipulada puede, por lo tanto, causar un consumo significativo de CPU y hacer que las aplicaciones que usan Mistune no respondan."
}
],
"affected": [
{
"source": "[email protected]",
"affectedData": [
{
"vendor": "lepture",
"product": "mistune",
"versions": [
{
"version": ">=3.0.0a1, <= 3.2.0",
"status": "affected"
}
]
}
]
},
{
"source": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c",
"affectedData": [
{
"vendor": "Red Hat",
"product": "Red Hat Migration Toolkit for Applications 8.2",
"defaultStatus": "affected",
"collectionURL": "https://catalog.redhat.com/software/containers/",
"packageName": "mta/mta-solution-server-rhel9",
"cpes": [
"cpe:/a:redhat:migration_toolkit_applications:8.2::el9"
],
"versions": [
{
"version": "1784109883",
"lessThan": "*",
"versionType": "rpm",
"status": "unaffected"
}
]
},
{
"vendor": "Red Hat",
"product": "Red Hat OpenShift AI 3.4",
"defaultStatus": "affected",
"collectionURL": "https://catalog.redhat.com/software/containers/",
"packageName": "rhoai/odh-pipeline-runtime-datascience-cpu-py312-rhel9",
"cpes": [
"cpe:/a:redhat:openshift_ai:3.4::el9"
],
"versions": [
{
"version": "1787073866",
"lessThan": "*",
"versionType": "rpm",
"status": "unaffected"
}
]
},
{
"vendor": "Red Hat",
"product": "Red Hat OpenShift AI 3.4",
"defaultStatus": "affected",
"collectionURL": "https://catalog.redhat.com/software/containers/",
"packageName": "rhoai/odh-pipeline-runtime-minimal-cpu-py312-rhel9",
"cpes": [
"cpe:/a:redhat:openshift_ai:3.4::el9"
],
"versions": [
{
"version": "1787073936",
"lessThan": "*",
"versionType": "rpm",
"status": "unaffected"
}
]
},
{
"vendor": "Red Hat",
"product": "Red Hat OpenShift AI 3.4",
"defaultStatus": "affected",
"collectionURL": "https://catalog.redhat.com/software/containers/",
"packageName": "rhoai/odh-pipeline-runtime-pytorch-cuda-py312-rhel9",
"cpes": [
"cpe:/a:redhat:openshift_ai:3.4::el9"
],
"versions": [
{
"version": "1787073873",
"lessThan": "*",
"versionType": "rpm",
"status": "unaffected"
}
]
},
{
"vendor": "Red Hat",
"product": "Red Hat OpenShift AI 3.4",
"defaultStatus": "affected",
"collectionURL": "https://catalog.redhat.com/software/containers/",
"packageName": "rhoai/odh-pipeline-runtime-pytorch-llmcompressor-cuda-py312-rhel9",
"cpes": [
"cpe:/a:redhat:openshift_ai:3.4::el9"
],
"versions": [
{
"version": "1787073459",
"lessThan": "*",
"versionType": "rpm",
"status": "unaffected"
}
]
},
{
"vendor": "Red Hat",
"product": "Red Hat OpenShift AI 3.4",
"defaultStatus": "affected",
"collectionURL": "https://catalog.redhat.com/software/containers/",
"packageName": "rhoai/odh-pipeline-runtime-pytorch-rocm-py312-rhel9",
"cpes": [
"cpe:/a:redhat:openshift_ai:3.4::el9"
],
"versions": [
{
"version": "1787073611",
"lessThan": "*",
"versionType": "rpm",
"status": "unaffected"
}
]
},
{
"vendor": "Red Hat",
"product": "Red Hat OpenShift AI 3.4",
"defaultStatus": "affected",
"collectionURL": "https://catalog.redhat.com/software/containers/",
"packageName": "rhoai/odh-pipeline-runtime-tensorflow-cuda-py312-rhel9",
"cpes": [
"cpe:/a:redhat:openshift_ai:3.4::el9"
],
"versions": [
{
"version": "1787073451",
"lessThan": "*",
"versionType": "rpm",
"status": "unaffected"
}
]
},
{
"vendor": "Red Hat",
"product": "Red Hat OpenShift AI 3.4",
"defaultStatus": "affected",
"collectionURL": "https://catalog.redhat.com/software/containers/",
"packageName": "rhoai/odh-pipeline-runtime-tensorflow-rocm-py312-rhel9",
"cpes": [
"cpe:/a:redhat:openshift_ai:3.4::el9"
],
"versions": [
{
"version": "1787073451",
"lessThan": "*",
"versionType": "rpm",
"status": "unaffected"
}
]
},
{
"vendor": "Red Hat",
"product": "Red Hat OpenShift AI 3.4",
"defaultStatus": "affected",
"collectionURL": "https://catalog.redhat.com/software/containers/",
"packageName": "rhoai/odh-th06-cpu-torch210-py312-rhel9",
"cpes": [
"cpe:/a:redhat:openshift_ai:3.4::el9"
],
"versions": [
{
"version": "1787076778",
"lessThan": "*",
"versionType": "rpm",
"status": "unaffected"
}
]
},
{
"vendor": "Red Hat",
"product": "Red Hat OpenShift AI 3.4",
"defaultStatus": "affected",
"collectionURL": "https://catalog.redhat.com/software/containers/",
"packageName": "rhoai/odh-th06-cuda130-torch210-py312-rhel9",
"cpes": [
"cpe:/a:redhat:openshift_ai:3.4::el9"
],
"versions": [
{
"version": "1787077779",
"lessThan": "*",
"versionType": "rpm",
"status": "unaffected"
}
]
},
{
"vendor": "Red Hat",
"product": "Red Hat OpenShift AI 3.4",
"defaultStatus": "affected",
"collectionURL": "https://catalog.redhat.com/software/containers/",
"packageName": "rhoai/odh-th06-rocm64-torch291-py312-rhel9",
"cpes": [
"cpe:/a:redhat:openshift_ai:3.4::el9"
],
"versions": [
{
"version": "1787076481",
"lessThan": "*",
"versionType": "rpm",
"status": "unaffected"
}
]
},
{
"vendor": "Red Hat",
"product": "Red Hat OpenShift AI 3.4",
"defaultStatus": "affected",
"collectionURL": "https://catalog.redhat.com/software/containers/",
"packageName": "rhoai/odh-workbench-jupyter-datascience-cpu-py312-rhel9",
"cpes": [
"cpe:/a:redhat:openshift_ai:3.4::el9"
],
"versions": [
{
"version": "1787074331",
"lessThan": "*",
"versionType": "rpm",
"status": "unaffected"
}
]
},
{
"vendor": "Red Hat",
"product": "Red Hat OpenShift AI 3.4",
"defaultStatus": "affected",
"collectionURL": "https://catalog.redhat.com/software/containers/",
"packageName": "rhoai/odh-workbench-jupyter-minimal-cpu-py312-rhel9",
"cpes": [
"cpe:/a:redhat:openshift_ai:3.4::el9"
],
"versions": [
{
"version": "1787073913",
"lessThan": "*",
"versionType": "rpm",
"status": "unaffected"
}
]
},
{
"vendor": "Red Hat",
"product": "Red Hat OpenShift AI 3.4",
"defaultStatus": "affected",
"collectionURL": "https://catalog.redhat.com/software/containers/",
"packageName": "rhoai/odh-workbench-jupyter-minimal-cuda-py312-rhel9",
"cpes": [
"cpe:/a:redhat:openshift_ai:3.4::el9"
],
"versions": [
{
"version": "1787074078",
"lessThan": "*",
"versionType": "rpm",
"status": "unaffected"
}
]
},
{
"vendor": "Red Hat",
"product": "Red Hat OpenShift AI 3.4",
"defaultStatus": "affected",
"collectionURL": "https://catalog.redhat.com/software/containers/",
"packageName": "rhoai/odh-workbench-jupyter-minimal-rocm-py312-rhel9",
"cpes": [
"cpe:/a:redhat:openshift_ai:3.4::el9"
],
"versions": [
{
"version": "1787073929",
"lessThan": "*",
"versionType": "rpm",
"status": "unaffected"
}
]
},
{
"vendor": "Red Hat",
"product": "Red Hat OpenShift AI 3.4",
"defaultStatus": "affected",
"collectionURL": "https://catalog.redhat.com/software/containers/",
"packageName": "rhoai/odh-workbench-jupyter-pytorch-cuda-py312-rhel9",
"cpes": [
"cpe:/a:redhat:openshift_ai:3.4::el9"
],
"versions": [
{
"version": "1787073605",
"lessThan": "*",
"versionType": "rpm",
"status": "unaffected"
}
]
},
{
"vendor": "Red Hat",
"product": "Red Hat OpenShift AI 3.4",
"defaultStatus": "affected",
"collectionURL": "https://catalog.redhat.com/software/containers/",
"packageName": "rhoai/odh-workbench-jupyter-pytorch-rocm-py312-rhel9",
"cpes": [
"cpe:/a:redhat:openshift_ai:3.4::el9"
],
"versions": [
{
"version": "1787073546",
"lessThan": "*",
"versionType": "rpm",
"status": "unaffected"
}
]
},
{
"vendor": "Red Hat",
"product": "Red Hat OpenShift AI 3.4",
"defaultStatus": "affected",
"collectionURL": "https://catalog.redhat.com/software/containers/",
"packageName": "rhoai/odh-workbench-jupyter-tensorflow-cuda-py312-rhel9",
"cpes": [
"cpe:/a:redhat:openshift_ai:3.4::el9"
],
"versions": [
{
"version": "1787073717",
"lessThan": "*",
"versionType": "rpm",
"status": "unaffected"
}
]
},
{
"vendor": "Red Hat",
"product": "Red Hat OpenShift AI 3.4",
"defaultStatus": "affected",
"collectionURL": "https://catalog.redhat.com/software/containers/",
"packageName": "rhoai/odh-workbench-jupyter-tensorflow-rocm-py312-rhel9",
"cpes": [
"cpe:/a:redhat:openshift_ai:3.4::el9"
],
"versions": [
{
"version": "1787073713",
"lessThan": "*",
"versionType": "rpm",
"status": "unaffected"
}
]
},
{
"vendor": "Red Hat",
"product": "Red Hat OpenShift AI 3.4",
"defaultStatus": "affected",
"collectionURL": "https://catalog.redhat.com/software/containers/",
"packageName": "rhoai/odh-workbench-jupyter-trustyai-cpu-py312-rhel9",
"cpes": [
"cpe:/a:redhat:openshift_ai:3.4::el9"
],
"versions": [
{
"version": "1787073593",
"lessThan": "*",
"versionType": "rpm",
"status": "unaffected"
}
]
},
{
"vendor": "Red Hat",
"product": "Red Hat OpenShift AI (RHOAI)",
"defaultStatus": "unaffected",
"collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
"packageName": "rhoai/odh-th06-cpu-torch291-py312-rhel9",
"cpes": [
"cpe:/a:redhat:openshift_ai"
]
},
{
"vendor": "Red Hat",
"product": "Red Hat OpenShift AI (RHOAI)",
"defaultStatus": "unaffected",
"collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
"packageName": "rhoai/odh-th06-cuda130-torch291-py312-rhel9",
"cpes": [
"cpe:/a:redhat:openshift_ai"
]
},
{
"vendor": "Red Hat",
"product": "Red Hat OpenShift AI (RHOAI)",
"defaultStatus": "affected",
"collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
"packageName": "rhoai/odh-workbench-jupyter-pytorch-llmcompressor-cuda-py312-rhel9",
"cpes": [
"cpe:/a:redhat:openshift_ai"
]
},
{
"vendor": "Red Hat",
"product": "Red Hat Satellite 6",
"defaultStatus": "unaffected",
"collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
"packageName": "satellite/iop-advisor-engine-rhel9",
"cpes": [
"cpe:/a:redhat:satellite:6"
]
}
]
}
],
"metrics": {
"cvssMetricV40": [
{
"source": "[email protected]",
"type": "Secondary",
"cvssData": {
"version": "4.0",
"vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
"baseScore": 8.7,
"baseSeverity": "HIGH",
"attackVector": "NETWORK",
"attackComplexity": "LOW",
"attackRequirements": "NONE",
"privilegesRequired": "NONE",
"userInteraction": "NONE",
"vulnConfidentialityImpact": "NONE",
"vulnIntegrityImpact": "NONE",
"vulnAvailabilityImpact": "HIGH",
"subConfidentialityImpact": "NONE",
"subIntegrityImpact": "NONE",
"subAvailabilityImpact": "NONE",
"exploitMaturity": "NOT_DEFINED",
"confidentialityRequirement": "NOT_DEFINED",
"integrityRequirement": "NOT_DEFINED",
"availabilityRequirement": "NOT_DEFINED",
"modifiedAttackVector": "NOT_DEFINED",
"modifiedAttackComplexity": "NOT_DEFINED",
"modifiedAttackRequirements": "NOT_DEFINED",
"modifiedPrivilegesRequired": "NOT_DEFINED",
"modifiedUserInteraction": "NOT_DEFINED",
"modifiedVulnConfidentialityImpact": "NOT_DEFINED",
"modifiedVulnIntegrityImpact": "NOT_DEFINED",
"modifiedVulnAvailabilityImpact": "NOT_DEFINED",
"modifiedSubConfidentialityImpact": "NOT_DEFINED",
"modifiedSubIntegrityImpact": "NOT_DEFINED",
"modifiedSubAvailabilityImpact": "NOT_DEFINED",
"Safety": "NOT_DEFINED",
"Automatable": "NOT_DEFINED",
"Recovery": "NOT_DEFINED",
"valueDensity": "NOT_DEFINED",
"vulnerabilityResponseEffort": "NOT_DEFINED",
"providerUrgency": "NOT_DEFINED"
}
}
],
"cvssMetricV31": [
{
"source": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c",
"type": "Secondary",
"cvssData": {
"version": "3.1",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
"baseScore": 7.5,
"baseSeverity": "HIGH",
"attackVector": "NETWORK",
"attackComplexity": "LOW",
"privilegesRequired": "NONE",
"userInteraction": "NONE",
"scope": "UNCHANGED",
"confidentialityImpact": "NONE",
"integrityImpact": "NONE",
"availabilityImpact": "HIGH"
},
"exploitabilityScore": 3.9,
"impactScore": 3.6
}
],
"ssvcV203": [
{
"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"ssvcData": {
"timestamp": "2026-05-06T19:02:37.046157Z",
"id": "CVE-2026-33079",
"options": [
{
"exploitation": "poc"
},
{
"automatable": "yes"
},
{
"technicalImpact": "partial"
}
],
"role": "CISA Coordinator",
"version": "2.0.3"
}
}
]
},
"weaknesses": [
{
"source": "[email protected]",
"type": "Secondary",
"description": [
{
"lang": "en",
"value": "CWE-1333"
}
]
},
{
"source": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c",
"type": "Secondary",
"description": [
{
"lang": "en",
"value": "CWE-1333"
}
]
}
],
"references": [
{
"url": "https://github.com/lepture/mistune/blob/df23edd60b43b639d2e6760ef9dd3d618aa11c21/src/mistune/helpers.py#L20-L25",
"source": "[email protected]"
},
{
"url": "https://github.com/lepture/mistune/security/advisories/GHSA-8mp2-v27r-99xp",
"source": "[email protected]"
},
{
"url": "https://access.redhat.com/errata/RHSA-2026:43038",
"source": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c"
},
{
"url": "https://access.redhat.com/errata/RHSA-2026:60520",
"source": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c"
},
{
"url": "https://access.redhat.com/security/cve/CVE-2026-33079",
"source": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c"
},
{
"url": "https://bugzilla.redhat.com/show_bug.cgi?id=2467298",
"source": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c"
},
{
"url": "https://github.com/lepture/mistune/security/advisories/GHSA-8mp2-v27r-99xp",
"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0"
},
{
"url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-33079.json",
"source": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c"
}
]
}