FKIE_CVE-2026-6658

Vulnerability from fkie_nvd - Published: 2026-06-26 10:16 - Updated: 2026-06-26 20:08
Severity ?
5.4 (Medium) - CVSS:3.0/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
Summary
A vulnerability in jupyter/nbconvert versions <= 7.17.0 allows for Cross-site Scripting (XSS) via unsanitized `text/vnd.mermaid` output in HTML exports. The `data_mermaid` block in `share/templates/lab/base.html.j2` renders `text/vnd.mermaid` cell output directly into HTML without escaping, enabling attackers to inject arbitrary HTML/JavaScript by breaking out of the `<pre>` tag. This vulnerability impacts any server using nbconvert to render notebooks as HTML, allowing attackers to execute arbitrary JavaScript in the context of users viewing the HTML export.
References
security@huntr.devhttps://huntr.com/bounties/47570290-3b26-4477-8cfa-fdef7db5aefe
134c704f-9b21-4f2e-91b3-4a467353bcc0https://huntr.com/bounties/47570290-3b26-4477-8cfa-fdef7db5aefe
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "product": "jupyter/jupyter",
          "vendor": "jupyter",
          "versions": [
            {
              "lessThanOrEqual": "latest",
              "status": "affected",
              "version": "unspecified",
              "versionType": "custom"
            }
          ]
        }
      ],
      "source": "security@huntr.dev"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "A vulnerability in jupyter/nbconvert versions \u003c= 7.17.0 allows for Cross-site Scripting (XSS) via unsanitized `text/vnd.mermaid` output in HTML exports. The `data_mermaid` block in `share/templates/lab/base.html.j2` renders `text/vnd.mermaid` cell output directly into HTML without escaping, enabling attackers to inject arbitrary HTML/JavaScript by breaking out of the `\u003cpre\u003e` tag. This vulnerability impacts any server using nbconvert to render notebooks as HTML, allowing attackers to execute arbitrary JavaScript in the context of users viewing the HTML export."
    }
  ],
  "id": "CVE-2026-6658",
  "lastModified": "2026-06-26T20:08:23.053",
  "metrics": {
    "cvssMetricV30": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "NONE",
          "baseScore": 5.4,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "LOW",
          "integrityImpact": "LOW",
          "privilegesRequired": "LOW",
          "scope": "CHANGED",
          "userInteraction": "REQUIRED",
          "vectorString": "CVSS:3.0/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N",
          "version": "3.0"
        },
        "exploitabilityScore": 2.3,
        "impactScore": 2.7,
        "source": "security@huntr.dev",
        "type": "Secondary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-6658",
          "options": [
            {
              "exploitation": "poc"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-06-26T10:19:03.505659Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2026-06-26T10:16:22.810",
  "references": [
    {
      "source": "security@huntr.dev",
      "url": "https://huntr.com/bounties/47570290-3b26-4477-8cfa-fdef7db5aefe"
    },
    {
      "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
      "url": "https://huntr.com/bounties/47570290-3b26-4477-8cfa-fdef7db5aefe"
    }
  ],
  "sourceIdentifier": "security@huntr.dev",
  "vulnStatus": "Deferred",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-79"
        }
      ],
      "source": "security@huntr.dev",
      "type": "Secondary"
    }
  ]
}


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  • Confirmed: The vulnerability has been validated from an analyst's perspective.
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  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.



Detection rules are retrieved from Rulezet.