CVE-2026-49851

Estado: AplazadaAlta (8.7)—

Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.3.0, Mistune is vulnerable to a CPU exhaustion DoS due to superlinear (approximately O(n²)) behavior in parse_link_text. When parsing Markdown containing many consecutive [ characters, parse_link_text repeatedly scans the input using a regex search inside a loop. Each iteration re-scans a large portion of the remaining string, resulting in quadratic-time behavior. An attacker-controlled Markdown input can therefore trigger excessive CPU usage with a very small payload. This vulnerability is fixed in 3.3.0.

CVSS

Versión: 4.0
Vector: 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
Puntuación base: 8.7

Probabilidad de explotación (EPSS)

Probabilidad de explotación en los próximos 30 días: 0.63%
Percentil entre todas las CVEs puntuadas: 48
Fecha de la puntuación: 6/10/2026

EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).

🎯 Técnicas ATT&CK

Cómo se explota esta vulnerabilidad y qué consigue el atacante, en el lenguaje de MITRE ATT&CK.

ExplotaciónT1190 Exploit Public-Facing Applicationinitial access85 %
Impacto principalT1499.004 Application or System Exploitationimpact90 %

Acceso remoto sin autenticación (AV:N/PR:N/UI:N) explotando entrada Markdown malformada. DoS por exhaustión CPU (VA:H) mediante payload pequeño con caracteres '[' consecutivos causa comportamiento O(n²).

Inferido por nuestro agente de análisis a partir de la descripción oficial, el vector CVSS y la CWE, y comprobado por un supervisor. Puede contener errores.

🛡️ Mitigaciones ATT&CK que cubren estas técnicas

Filter Network Traffic Vulnerability Scanning Privileged Account Management Network Segmentation Limit Access to Resource Over Network Application Isolation and Sandboxing

Tecnologías afectadas (1)

⚠ Inferidas por IA a partir de la descripción — NVD aún no ha analizado esta CVE; no son CPE verificados.

Mistune — Mistune^AI

CWE

CWE-400, CWE-407, CWE-770
CWE-1333

Referencias

JSON original (NVD)

Mostrar

{
  "id": "CVE-2026-49851",
  "cveTags": [],
  "metrics": {
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-49851",
          "role": "CISA Coordinator",
          "options": [
            {
              "exploitation": "poc"
            },
            {
              "automatable": "yes"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "version": "2.0.3",
          "timestamp": "2026-06-25T19:55:32.245725Z"
        }
      }
    ],
    "cvssMetricV31": [
      {
        "type": "Secondary",
        "source": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c",
        "cvssData": {
          "scope": "UNCHANGED",
          "version": "3.1",
          "baseScore": 7.5,
          "attackVector": "NETWORK",
          "baseSeverity": "HIGH",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
          "integrityImpact": "NONE",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "confidentialityImpact": "NONE"
        },
        "impactScore": 3.6,
        "exploitabilityScore": 3.9
      }
    ],
    "cvssMetricV40": [
      {
        "type": "Secondary",
        "source": "security-advisories@github.com",
        "cvssData": {
          "Safety": "NOT_DEFINED",
          "version": "4.0",
          "Recovery": "NOT_DEFINED",
          "baseScore": 8.7,
          "Automatable": "NOT_DEFINED",
          "attackVector": "NETWORK",
          "baseSeverity": "HIGH",
          "valueDensity": "NOT_DEFINED",
          "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",
          "exploitMaturity": "NOT_DEFINED",
          "providerUrgency": "NOT_DEFINED",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "attackRequirements": "NONE",
          "privilegesRequired": "NONE",
          "subIntegrityImpact": "NONE",
          "vulnIntegrityImpact": "NONE",
          "integrityRequirement": "NOT_DEFINED",
          "modifiedAttackVector": "NOT_DEFINED",
          "subAvailabilityImpact": "NONE",
          "vulnAvailabilityImpact": "HIGH",
          "availabilityRequirement": "NOT_DEFINED",
          "modifiedUserInteraction": "NOT_DEFINED",
          "modifiedAttackComplexity": "NOT_DEFINED",
          "subConfidentialityImpact": "NONE",
          "vulnConfidentialityImpact": "NONE",
          "confidentialityRequirement": "NOT_DEFINED",
          "modifiedAttackRequirements": "NOT_DEFINED",
          "modifiedPrivilegesRequired": "NOT_DEFINED",
          "modifiedSubIntegrityImpact": "NOT_DEFINED",
          "modifiedVulnIntegrityImpact": "NOT_DEFINED",
          "vulnerabilityResponseEffort": "NOT_DEFINED",
          "modifiedSubAvailabilityImpact": "NOT_DEFINED",
          "modifiedVulnAvailabilityImpact": "NOT_DEFINED",
          "modifiedSubConfidentialityImpact": "NOT_DEFINED",
          "modifiedVulnConfidentialityImpact": "NOT_DEFINED"
        }
      }
    ]
  },
  "affected": [
    {
      "source": "security-advisories@github.com",
      "affectedData": [
        {
          "vendor": "lepture",
          "product": "mistune",
          "versions": [
            {
              "status": "affected",
              "version": "< 3.3.0"
            }
          ]
        }
      ]
    },
    {
      "source": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c",
      "affectedData": [
        {
          "cpes": [
            "cpe:/a:redhat:openshift_ai:3.4::el9"
          ],
          "vendor": "Red Hat",
          "product": "Red Hat OpenShift AI 3.4",
          "versions": [
            {
              "status": "unaffected",
              "version": "1787073866",
              "lessThan": "*",
              "versionType": "rpm"
            }
          ],
          "packageName": "rhoai/odh-pipeline-runtime-datascience-cpu-py312-rhel9",
          "collectionURL": "https://catalog.redhat.com/software/containers/",
          "defaultStatus": "affected"
        },
        {
          "cpes": [
            "cpe:/a:redhat:openshift_ai:3.4::el9"
          ],
          "vendor": "Red Hat",
          "product": "Red Hat OpenShift AI 3.4",
          "versions": [
            {
              "status": "unaffected",
              "version": "1787073936",
              "lessThan": "*",
              "versionType": "rpm"
            }
          ],
          "packageName": "rhoai/odh-pipeline-runtime-minimal-cpu-py312-rhel9",
          "collectionURL": "https://catalog.redhat.com/software/containers/",
          "defaultStatus": "affected"
        },
        {
          "cpes": [
            "cpe:/a:redhat:openshift_ai:3.4::el9"
          ],
          "vendor": "Red Hat",
          "product": "Red Hat OpenShift AI 3.4",
          "versions": [
            {
              "status": "unaffected",
              "version": "1787073873",
              "lessThan": "*",
              "versionType": "rpm"
            }
          ],
          "packageName": "rhoai/odh-pipeline-runtime-pytorch-cuda-py312-rhel9",
          "collectionURL": "https://catalog.redhat.com/software/containers/",
          "defaultStatus": "affected"
        },
        {
          "cpes": [
            "cpe:/a:redhat:openshift_ai:3.4::el9"
          ],
          "vendor": "Red Hat",
          "product": "Red Hat OpenShift AI 3.4",
          "versions": [
            {
              "status": "unaffected",
              "version": "1787073459",
              "lessThan": "*",
              "versionType": "rpm"
            }
          ],
          "packageName": "rhoai/odh-pipeline-runtime-pytorch-llmcompressor-cuda-py312-rhel9",
          "collectionURL": "https://catalog.redhat.com/software/containers/",
          "defaultStatus": "affected"
        },
        {
          "cpes": [
            "cpe:/a:redhat:openshift_ai:3.4::el9"
          ],
          "vendor": "Red Hat",
          "product": "Red Hat OpenShift AI 3.4",
          "versions": [
            {
              "status": "unaffected",
              "version": "1787073611",
              "lessThan": "*",
              "versionType": "rpm"
            }
          ],
          "packageName": "rhoai/odh-pipeline-runtime-pytorch-rocm-py312-rhel9",
          "collectionURL": "https://catalog.redhat.com/software/containers/",
          "defaultStatus": "affected"
        },
        {
          "cpes": [
            "cpe:/a:redhat:openshift_ai:3.4::el9"
          ],
          "vendor": "Red Hat",
          "product": "Red Hat OpenShift AI 3.4",
          "versions": [
            {
              "status": "unaffected",
              "version": "1787073451",
              "lessThan": "*",
              "versionType": "rpm"
            }
          ],
          "packageName": "rhoai/odh-pipeline-runtime-tensorflow-cuda-py312-rhel9",
          "collectionURL": "https://catalog.redhat.com/software/containers/",
          "defaultStatus": "affected"
        },
        {
          "cpes": [
            "cpe:/a:redhat:openshift_ai:3.4::el9"
          ],
          "vendor": "Red Hat",
          "product": "Red Hat OpenShift AI 3.4",
          "versions": [
            {
              "status": "unaffected",
              "version": "1787073451",
              "lessThan": "*",
              "versionType": "rpm"
            }
          ],
          "packageName": "rhoai/odh-pipeline-runtime-tensorflow-rocm-py312-rhel9",
          "collectionURL": "https://catalog.redhat.com/software/containers/",
          "defaultStatus": "affected"
        },
        {
          "cpes": [
            "cpe:/a:redhat:openshift_ai:3.4::el9"
          ],
          "vendor": "Red Hat",
          "product": "Red Hat OpenShift AI 3.4",
          "versions": [
            {
              "status": "unaffected",
              "version": "1787076778",
              "lessThan": "*",
              "versionType": "rpm"
            }
          ],
          "packageName": "rhoai/odh-th06-cpu-torch210-py312-rhel9",
          "collectionURL": "https://catalog.redhat.com/software/containers/",
          "defaultStatus": "affected"
        },
        {
          "cpes": [
            "cpe:/a:redhat:openshift_ai:3.4::el9"
          ],
          "vendor": "Red Hat",
          "product": "Red Hat OpenShift AI 3.4",
          "versions": [
            {
              "status": "unaffected",
              "version": "1787077779",
              "lessThan": "*",
              "versionType": "rpm"
            }
          ],
          "packageName": "rhoai/odh-th06-cuda130-torch210-py312-rhel9",
          "collectionURL": "https://catalog.redhat.com/software/containers/",
          "defaultStatus": "affected"
        },
        {
          "cpes": [
            "cpe:/a:redhat:openshift_ai:3.4::el9"
          ],
          "vendor": "Red Hat",
          "product": "Red Hat OpenShift AI 3.4",
          "versions": [
            {
              "status": "unaffected",
              "version": "1787076481",
              "lessThan": "*",
              "versionType": "rpm"
            }
          ],
          "packageName": "rhoai/odh-th06-rocm64-torch291-py312-rhel9",
          "collectionURL": "https://catalog.redhat.com/software/containers/",
          "defaultStatus": "affected"
        },
        {
          "cpes": [
            "cpe:/a:redhat:openshift_ai:3.4::el9"
          ],
          "vendor": "Red Hat",
          "product": "Red Hat OpenShift AI 3.4",
          "versions": [
            {
              "status": "unaffected",
              "version": "1787074331",
              "lessThan": "*",
              "versionType": "rpm"
            }
          ],
          "packageName": "rhoai/odh-workbench-jupyter-datascience-cpu-py312-rhel9",
          "collectionURL": "https://catalog.redhat.com/software/containers/",
          "defaultStatus": "affected"
        },
        {
          "cpes": [
            "cpe:/a:redhat:openshift_ai:3.4::el9"
          ],
          "vendor": "Red Hat",
          "product": "Red Hat OpenShift AI 3.4",
          "versions": [
            {
              "status": "unaffected",
              "version": "1787073913",
              "lessThan": "*",
              "versionType": "rpm"
            }
          ],
          "packageName": "rhoai/odh-workbench-jupyter-minimal-cpu-py312-rhel9",
          "collectionURL": "https://catalog.redhat.com/software/containers/",
          "defaultStatus": "affected"
        },
        {
          "cpes": [
            "cpe:/a:redhat:openshift_ai:3.4::el9"
          ],
          "vendor": "Red Hat",
          "product": "Red Hat OpenShift AI 3.4",
          "versions": [
            {
              "status": "unaffected",
              "version": "1787074078",
              "lessThan": "*",
              "versionType": "rpm"
            }
          ],
          "packageName": "rhoai/odh-workbench-jupyter-minimal-cuda-py312-rhel9",
          "collectionURL": "https://catalog.redhat.com/software/containers/",
          "defaultStatus": "affected"
        },
        {
          "cpes": [
            "cpe:/a:redhat:openshift_ai:3.4::el9"
          ],
          "vendor": "Red Hat",
          "product": "Red Hat OpenShift AI 3.4",
          "versions": [
            {
              "status": "unaffected",
              "version": "1787073929",
              "lessThan": "*",
              "versionType": "rpm"
            }
          ],
          "packageName": "rhoai/odh-workbench-jupyter-minimal-rocm-py312-rhel9",
          "collectionURL": "https://catalog.redhat.com/software/containers/",
          "defaultStatus": "affected"
        },
        {
          "cpes": [
            "cpe:/a:redhat:openshift_ai:3.4::el9"
          ],
          "vendor": "Red Hat",
          "product": "Red Hat OpenShift AI 3.4",
          "versions": [
            {
              "status": "unaffected",
              "version": "1787073605",
              "lessThan": "*",
              "versionType": "rpm"
            }
          ],
          "packageName": "rhoai/odh-workbench-jupyter-pytorch-cuda-py312-rhel9",
          "collectionURL": "https://catalog.redhat.com/software/containers/",
          "defaultStatus": "affected"
        },
        {
          "cpes": [
            "cpe:/a:redhat:openshift_ai:3.4::el9"
          ],
          "vendor": "Red Hat",
          "product": "Red Hat OpenShift AI 3.4",
          "versions": [
            {
              "status": "unaffected",
              "version": "1787073546",
              "lessThan": "*",
              "versionType": "rpm"
            }
          ],
          "packageName": "rhoai/odh-workbench-jupyter-pytorch-rocm-py312-rhel9",
          "collectionURL": "https://catalog.redhat.com/software/containers/",
          "defaultStatus": "affected"
        },
        {
          "cpes": [
            "cpe:/a:redhat:openshift_ai:3.4::el9"
          ],
          "vendor": "Red Hat",
          "product": "Red Hat OpenShift AI 3.4",
          "versions": [
            {
              "status": "unaffected",
              "version": "1787073717",
              "lessThan": "*",
              "versionType": "rpm"
            }
          ],
          "packageName": "rhoai/odh-workbench-jupyter-tensorflow-cuda-py312-rhel9",
          "collectionURL": "https://catalog.redhat.com/software/containers/",
          "defaultStatus": "affected"
        },
        {
          "cpes": [
            "cpe:/a:redhat:openshift_ai:3.4::el9"
          ],
          "vendor": "Red Hat",
          "product": "Red Hat OpenShift AI 3.4",
          "versions": [
            {
              "status": "unaffected",
              "version": "1787073713",
              "lessThan": "*",
              "versionType": "rpm"
            }
          ],
          "packageName": "rhoai/odh-workbench-jupyter-tensorflow-rocm-py312-rhel9",
          "collectionURL": "https://catalog.redhat.com/software/containers/",
          "defaultStatus": "affected"
        },
        {
          "cpes": [
            "cpe:/a:redhat:openshift_ai:3.4::el9"
          ],
          "vendor": "Red Hat",
          "product": "Red Hat OpenShift AI 3.4",
          "versions": [
            {
              "status": "unaffected",
              "version": "1787073593",
              "lessThan": "*",
              "versionType": "rpm"
            }
          ],
          "packageName": "rhoai/odh-workbench-jupyter-trustyai-cpu-py312-rhel9",
          "collectionURL": "https://catalog.redhat.com/software/containers/",
          "defaultStatus": "affected"
        },
        {
          "cpes": [
            "cpe:/a:redhat:migration_toolkit_applications:8"
          ],
          "vendor": "Red Hat",
          "product": "Migration Toolkit for Applications 8",
          "packageName": "mta/mta-solution-server-rhel9",
          "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
          "defaultStatus": "unaffected"
        },
        {
          "cpes": [
            "cpe:/a:redhat:openshift_ai"
          ],
          "vendor": "Red Hat",
          "product": "Red Hat OpenShift AI (RHOAI)",
          "packageName": "rhoai/odh-th06-cpu-torch291-py312-rhel9",
          "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
          "defaultStatus": "unaffected"
        },
        {
          "cpes": [
            "cpe:/a:redhat:openshift_ai"
          ],
          "vendor": "Red Hat",
          "product": "Red Hat OpenShift AI (RHOAI)",
          "packageName": "rhoai/odh-th06-cuda130-torch291-py312-rhel9",
          "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
          "defaultStatus": "unaffected"
        },
        {
          "cpes": [
            "cpe:/a:redhat:openshift_ai"
          ],
          "vendor": "Red Hat",
          "product": "Red Hat OpenShift AI (RHOAI)",
          "packageName": "rhoai/odh-workbench-jupyter-pytorch-llmcompressor-cuda-py312-rhel9",
          "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
          "defaultStatus": "affected"
        },
        {
          "cpes": [
            "cpe:/a:redhat:openshift:4"
          ],
          "vendor": "Red Hat",
          "product": "Red Hat OpenShift Container Platform 4",
          "packageName": "python-mistune",
          "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
          "defaultStatus": "unaffected"
        },
        {
          "cpes": [
            "cpe:/a:redhat:satellite:6"
          ],
          "vendor": "Red Hat",
          "product": "Red Hat Satellite 6",
          "packageName": "satellite/iop-advisor-engine-rhel9",
          "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
          "defaultStatus": "unaffected"
        }
      ]
    }
  ],
  "published": "2026-06-24T18:17:18.937",
  "references": [
    {
      "url": "https://github.com/lepture/mistune/security/advisories/GHSA-qcq2-496w-v96p",
      "source": "security-advisories@github.com"
    },
    {
      "url": "https://access.redhat.com/errata/RHSA-2026:60520",
      "source": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c"
    },
    {
      "url": "https://access.redhat.com/security/cve/CVE-2026-49851",
      "source": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c"
    },
    {
      "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2492304",
      "source": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c"
    },
    {
      "url": "https://github.com/lepture/mistune/security/advisories/GHSA-qcq2-496w-v96p",
      "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0"
    },
    {
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-49851.json",
      "source": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c"
    }
  ],
  "vulnStatus": "Deferred",
  "weaknesses": [
    {
      "type": "Secondary",
      "source": "security-advisories@github.com",
      "description": [
        {
          "lang": "en",
          "value": "CWE-400"
        },
        {
          "lang": "en",
          "value": "CWE-407"
        },
        {
          "lang": "en",
          "value": "CWE-770"
        }
      ]
    },
    {
      "type": "Secondary",
      "source": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c",
      "description": [
        {
          "lang": "en",
          "value": "CWE-1333"
        }
      ]
    }
  ],
  "descriptions": [
    {
      "lang": "en",
      "value": "Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.3.0, Mistune is vulnerable to a CPU exhaustion DoS due to superlinear (approximately O(n²)) behavior in parse_link_text. When parsing Markdown containing many consecutive [ characters, parse_link_text repeatedly scans the input using a regex search inside a loop. Each iteration re-scans a large portion of the remaining string, resulting in quadratic-time behavior. An attacker-controlled Markdown input can therefore trigger excessive CPU usage with a very small payload. This vulnerability is fixed in 3.3.0."
    }
  ],
  "lastModified": "2026-08-28T16:18:13.200",
  "sourceIdentifier": "security-advisories@github.com"
}