BREW-JUPYTERLAB-CVE-2020-6802 (GHSA-Q65M-PV3F-WR5R)

Vulnerability from osv_homebrew – Published: 2026-08-13 17:01 – Updated: 2026-09-17 19:02 – Source website
VLAI
Summary
XSS in Bleach when noscript and raw tag whitelisted
Details

Impact

A mutation XSS affects users calling bleach.clean with noscript and a raw tag (see below) in the allowed/whitelisted tags option.

Patches

v3.1.1

Workarounds

  • modify bleach.clean calls to not whitelist noscript and one or more of the following raw tags:
title
textarea
script
style
noembed
noframes
iframe
xmp

References

  • https://bugzilla.mozilla.org/show_bug.cgi?id=1615315
  • https://cure53.de/fp170.pdf
  • https://nvd.nist.gov/vuln/detail/CVE-2020-6802
  • https://www.checkmarx.com/blog/vulnerabilities-discovered-in-mozilla-bleach

Credits

  • Reported by Yaniv Nizry from the CxSCA AppSec group at Checkmarx

For more information

If you have any questions or comments about this advisory:

Severity
6.1 (Medium)
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
5.3 (Medium)
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N
References
To clipboard 

{
  "affected": [
    {
      "ecosystem_specific": {
        "fix": "bump",
        "range_state": "fixed",
        "resource": "bleach",
        "resource_purl": "pkg:pypi/bleach@6.4.0",
        "upstream_fixed_in": "3.1.1"
      },
      "package": {
        "ecosystem": "Homebrew",
        "name": "jupyterlab",
        "purl": "pkg:brew/jupyterlab"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "1.2.0"
            },
            {
              "fixed": "2.0.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "database_specific": {
    "confidence": "high",
    "source": "matched",
    "strategy": "registry",
    "upstream_evidence": [
      {
        "ecosystem": "PyPI",
        "key": "pkg:pypi/bleach@6.4.0",
        "name": "bleach",
        "resource": "bleach",
        "strategy": "registry",
        "subject_version": "6.4.0"
      }
    ]
  },
  "details": "### Impact\n\nA [mutation XSS](https://cure53.de/fp170.pdf) affects users calling `bleach.clean` with `noscript` and a raw tag (see below) in the allowed/whitelisted tags option.\n\n### Patches\n\nv3.1.1\n\n### Workarounds\n\n* modify `bleach.clean` calls to not whitelist `noscript` and one or more of the following raw tags:\n\n```\ntitle\ntextarea\nscript\nstyle\nnoembed\nnoframes\niframe\nxmp\n```\n\n* A strong [Content-Security-Policy](https://developer.mozilla.org/en-US/docs/Web/HTTP/CSP) without `unsafe-inline` and `unsafe-eval` [`script-src`s](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Content-Security-Policy/script-src)) will also help mitigate the risk.\n\n### References\n\n* https://bugzilla.mozilla.org/show_bug.cgi?id=1615315\n* https://cure53.de/fp170.pdf\n* https://nvd.nist.gov/vuln/detail/CVE-2020-6802\n* https://www.checkmarx.com/blog/vulnerabilities-discovered-in-mozilla-bleach\n\n### Credits\n\n* Reported by [Yaniv Nizry](https://twitter.com/ynizry) from the CxSCA AppSec group at Checkmarx\n\n### For more information\n\nIf you have any questions or comments about this advisory:\n\n* Open an issue at [https://github.com/mozilla/bleach/issues](https://github.com/mozilla/bleach/issues)\n* Email us at [security@mozilla.org](mailto:security@mozilla.org)\n",
  "id": "BREW-jupyterlab-CVE-2020-6802",
  "modified": "2026-09-17T19:02:18Z",
  "published": "2026-08-13T17:01:18Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/mozilla/bleach/security/advisories/GHSA-q65m-pv3f-wr5r"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2020-6802"
    },
    {
      "type": "WEB",
      "url": "https://github.com/mozilla/bleach/commit/f77e0f6392177a06e46a49abd61a4d9f035e57fd"
    },
    {
      "type": "WEB",
      "url": "https://advisory.checkmarx.net/advisory/CX-2020-4276"
    },
    {
      "type": "WEB",
      "url": "https://bugzilla.mozilla.org/show_bug.cgi?id=1615315"
    },
    {
      "type": "WEB",
      "url": "https://cure53.de/fp170.pdf"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/mozilla/bleach"
    },
    {
      "type": "WEB",
      "url": "https://github.com/pypa/advisory-database/tree/main/vulns/bleach/PYSEC-2020-27.yaml"
    },
    {
      "type": "WEB",
      "url": "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/72R4VFFHDRSQMNT7IZU3X2755ZP4HGNI"
    },
    {
      "type": "WEB",
      "url": "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/OCNLM2MGQTOLCIVVYS2Z5S7KOQJR5JC4"
    },
    {
      "type": "WEB",
      "url": "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/YTULPQB7HVPPYWEYVNHJGDTSPVIDHIZX"
    },
    {
      "type": "WEB",
      "url": "https://www.checkmarx.com/blog/vulnerabilities-discovered-in-mozilla-bleach"
    }
  ],
  "schema_version": "1.7.3",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N",
      "type": "CVSS_V3"
    },
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "XSS in Bleach when noscript and raw tag whitelisted",
  "upstream": [
    "GHSA-q65m-pv3f-wr5r",
    "CVE-2020-6802",
    "PYSEC-2020-27"
  ]
}



Log in or create an account to share your comment.




Tags
Taxonomy of the tags.




Drag nodes to arrange them. Double-click a related vulnerability to open it, or a source to visit its link. The Physics button on the left tunes the layout and the simulation; the legend at the bottom left hides or shows nodes by kind and by sighting type.

Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

Author Source Type Date Other

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
Vulnerability timeline

Sightings and recorded dates, grouped by day · UTC

JSON
How durations are calculated

Following the VTEM framework (Black Hat USA 2015), time to patch starts when the vendor or a coordinator was informed, total time to patch at discovery, and disclosure to patch at public disclosure; vendor response time runs from the report to its acknowledgement. Time to exploit and time unpatched start at the earliest discovery or report, falling back to public disclosure. Unpatched time ends at the first recorded patch, or the calculation time when no patch is recorded. Exploitation to patch shows the interval between those two events; a published proof of concept is a public exploit, not exploitation.

Each result shows its source dates. A negative interval means the end event came first; when date-only inputs leave the order open, the result says so. Date-only inputs are approximate. The earliest evidence wins: KEV report dates and sightings are labelled as such. Records describing another vulnerability are listed but never calculated from, and a PoC alone does not establish exploitation. Missing patch evidence does not prove that no patch exists. Filters below change the event list only.

Loading timeline…




    Related by attack behaviour

    Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.