CVE-2026-86049

Estado: Pendiente de análisisAlta (7.1)—

Jupyter Server is the backend for Jupyter web applications. Prior to version 2.21.0, the 5xx request logging path in jupyter_server/log.py copies the Referer header into a JSON header block without applying the token scrubbing used for the request URI. A request that returns HTTP 500 while the Referer contains a token-bearing URL can therefore write that token to server logs in plaintext. An attacker who can read those logs can recover the token and use the affected user's Jupyter Server permissions. This issue is fixed in version 2.21.0.

CVSS

Versión: 3.1
Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:H/I:H/A:H
Puntuación base: 7.1

Probabilidad de explotación (EPSS)

Probabilidad de explotación en los próximos 30 días: 0.42%
Percentil entre todas las CVEs puntuadas: 34
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.

ExplotaciónT1203 Exploitation for Client Executionexecution75 %
Impacto principalT1552.001 Credentials In Filescredential access85 %
Impacto secundarioT1078.001 Default Accountsstealth · persistence · privilege escalation · initial access70 %

CVE afecta logging de errores 5xx sin sanitizar Referer; atacante obtiene token en logs (T1552.001) para autenticarse como usuario legítimo (T1078.001) tras inducir request 500 con UI:R.

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

Password Policies User Training Restrict File and Directory Permissions Multi-factor Authentication Audit 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.

Jupyter — Jupyter Server^AI

CWE

CWE-532

Referencias

JSON original (NVD)

Mostrar

{
  "id": "CVE-2026-86049",
  "cveTags": [],
  "metrics": {
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-86049",
          "role": "CISA Coordinator",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "total"
            }
          ],
          "version": "2.0.3",
          "timestamp": "2026-09-18T17:24:12.266474Z"
        }
      }
    ],
    "cvssMetricV31": [
      {
        "type": "Secondary",
        "source": "security-advisories@github.com",
        "cvssData": {
          "scope": "UNCHANGED",
          "version": "3.1",
          "baseScore": 7.1,
          "attackVector": "NETWORK",
          "baseSeverity": "HIGH",
          "vectorString": "CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:H/I:H/A:H",
          "integrityImpact": "HIGH",
          "userInteraction": "REQUIRED",
          "attackComplexity": "HIGH",
          "availabilityImpact": "HIGH",
          "privilegesRequired": "LOW",
          "confidentialityImpact": "HIGH"
        },
        "impactScore": 5.9,
        "exploitabilityScore": 1.2
      }
    ]
  },
  "affected": [
    {
      "source": "security-advisories@github.com",
      "affectedData": [
        {
          "vendor": "jupyter-server",
          "product": "jupyter_server",
          "versions": [
            {
              "status": "affected",
              "version": "< 2.21.0"
            }
          ]
        }
      ]
    }
  ],
  "published": "2026-09-17T21:17:50.213",
  "references": [
    {
      "url": "https://github.com/jupyter-server/jupyter_server/commit/52513529af7096e622c00911b17627b266294717",
      "source": "security-advisories@github.com"
    },
    {
      "url": "https://github.com/jupyter-server/jupyter_server/pull/1681",
      "source": "security-advisories@github.com"
    },
    {
      "url": "https://github.com/jupyter-server/jupyter_server/releases/tag/v2.21.0",
      "source": "security-advisories@github.com"
    },
    {
      "url": "https://github.com/jupyter-server/jupyter_server/security/advisories/GHSA-c3mw-737p-c7g2",
      "source": "security-advisories@github.com"
    }
  ],
  "vulnStatus": "Awaiting Analysis",
  "weaknesses": [
    {
      "type": "Secondary",
      "source": "security-advisories@github.com",
      "description": [
        {
          "lang": "en",
          "value": "CWE-532"
        }
      ]
    }
  ],
  "descriptions": [
    {
      "lang": "en",
      "value": "Jupyter Server is the backend for Jupyter web applications. Prior to version 2.21.0, the 5xx request logging path in jupyter_server/log.py copies the Referer header into a JSON header block without applying the token scrubbing used for the request URI. A request that returns HTTP 500 while the Referer contains a token-bearing URL can therefore write that token to server logs in plaintext. An attacker who can read those logs can recover the token and use the affected user's Jupyter Server permissions. This issue is fixed in version 2.21.0."
    }
  ],
  "lastModified": "2026-09-24T21:19:05.340",
  "sourceIdentifier": "security-advisories@github.com"
}