Vulnerability-Lookup

GSD-2020-6817

Vulnerability from gsd - Updated: 2023-12-13 01:21

Details

bleach.clean behavior parsing style attributes could result in a regular expression denial of service (ReDoS). Calls to bleach.clean with an allowed tag with an allowed style attribute are vulnerable to ReDoS. For example, bleach.clean(..., attributes={'a': ['style']}).

Aliases

CVE-2020-6817

Aliases

CVE-2020-6817

JSON

To clipboard

{
  "GSD": {
    "alias": "CVE-2020-6817",
    "id": "GSD-2020-6817",
    "references": [
      "https://www.suse.com/security/cve/CVE-2020-6817.html",
      "https://advisories.mageia.org/CVE-2020-6817.html"
    ]
  },
  "gsd": {
    "metadata": {
      "exploitCode": "unknown",
      "remediation": "unknown",
      "reportConfidence": "confirmed",
      "type": "vulnerability"
    },
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        "CVE-2020-6817"
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      "id": "GSD-2020-6817",
      "modified": "2023-12-13T01:21:54.784364Z",
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    }
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      "advisories": [
        {
          "affected_range": "\u003c3.1.4",
          "affected_versions": "All versions before 3.1.4",
          "cwe_ids": [
            "CWE-1035",
            "CWE-937"
          ],
          "date": "2021-08-23",
          "description": "### Impact\n\n`bleach.clean` behavior parsing style attributes could result in a regular expression denial of service .\n\nCalls to ``bleach.clean`` with an allowed tag with an allowed ``style`` attribute are vulnerable to ReDoS. For example, ``bleach.clean(..., attributes={\u0027a\u0027: \u0027style\u0027 Workarounds\n\n* do not allowlist the style attribute in `bleach.clean` calls\n\n* limit input string length\n\n### References\n\n* https://bugzilla.mozilla.org/show_bug.cgi?id=1623633\n* https://www.regular-expressions.info/redos.html\n* https://blog.r2c.dev/posts/finding-python-redos-bugs-at-scale-using-dlint-and-r2c/\n* https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-6817\n\n### Credits\n\n* Reported by schwag09 of r2c\n\n### For more information\nIf you have any questions or comments about this advisory:\n\n* Open an issue at https://github.com/mozilla/bleach/issues\n* Email us at security@mozilla.org",
          "fixed_versions": [
            "3.1.4"
          ],
          "identifier": "GMS-2020-698",
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            "GMS-2020-698",
            "CVE-2020-6817"
          ],
          "not_impacted": "All versions starting from 3.1.4",
          "package_slug": "pypi/bleach",
          "pubdate": "2020-03-30",
          "solution": "Upgrade to version 3.1.4 or above.",
          "title": "regular expression denial-of-service  in Bleach",
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            "https://github.com/mozilla/bleach/security/advisories/GHSA-vqhp-cxgc-6wmm",
            "https://bugzilla.mozilla.org/show_bug.cgi?id=1623633",
            "https://github.com/mozilla/bleach/releases/tag/v3.1.4",
            "https://nvd.nist.gov/vuln/detail/CVE-2020-6817",
            "https://snyk.io/vuln/SNYK-PYTHON-BLEACH-561754",
            "https://github.com/advisories/GHSA-vqhp-cxgc-6wmm"
          ],
          "uuid": "55a10afd-a2bb-4082-b092-81d2505527e3"
        }
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                "vulnerable": true
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          "impactScore": 3.6
        }
      },
      "lastModifiedDate": "2023-02-28T14:46Z",
      "publishedDate": "2023-02-16T22:15Z"
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}

CVE-2020-6817 (GCVE-0-2020-6817)

Vulnerability from cvelistv5 – Published: 2023-02-16 00:00 – Updated: 2025-03-19 15:21

Summary

Severity

7.5 (High)


                        
                          CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

SSVC

Exploitation: poc Automatable: yes Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2025-03-19 15:21 UTC

CWE

regular expression denial-of-service (ReDoS) in BleachSanitizerFilter.sanitize_css gauntlet regular expression
CWE-1333 - Inefficient Regular Expression Complexity

Assigner

mozilla mitre root

References

2 references

URL	Tags
https://github.com/mozilla/bleach/security/adviso…
https://bugzilla.mozilla.org/show_bug.cgi?id=1623633

Impacted products

1 product

Vendor	Product	Version
Mozilla	Mozilla Bleach	Affected: unspecified , < 3.1.4 (custom)

Show details on NVD website

JSON

To clipboard

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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.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

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.