Vulnerability-Lookup

GHSA-C486-5FVQ-FP3V

Vulnerability from github – Published: 2026-08-06 18:30 – Updated: 2026-08-19 12:32

Details

This is not cross-site scripting. Browsers do not navigate a meta refresh to a javascript: URL, so the uppercase JAVASCRIPT: filter bypass yields no script execution and none was demonstrated.

This issue affects html_sanitize_ex: from 0.3.1 before 1.5.3.

Severity

6.1 (Medium)


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

2.3 (Low)


                  
                    CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:N/VI:N/VA:N/SC:N/SI:L/SA:N

Show details on source website

JSON

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{
  "affected": [],
  "aliases": [
    "CVE-2026-66829"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-601"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-08-06T16:16:49Z",
    "severity": "LOW"
  },
  "details": "URL Redirection to Untrusted Site (\u0027Open Redirect\u0027) vulnerability in the HTML5 scrubber in rrrene html_sanitize_ex allows a remote attacker to force visitors of a page to navigate to a site of the attacker\u0027s choosing via a \u003cmeta http-equiv=\"refresh\"\u003e element in sanitized HTML. HtmlSanitizeEx.html5/1 keeps attacker-supplied \u003cmeta\u003e elements in its output. A meta element acts on the whole document rather than on the fragment it was embedded in, so it can also declare document-wide directives such as Content-Security-Policy.\n\nThis is not cross-site scripting. Browsers do not navigate a meta refresh to a javascript: URL, so the uppercase JAVASCRIPT: filter bypass yields no script execution and none was demonstrated.\n\nThis issue affects html_sanitize_ex: from 0.3.1 before 1.5.3.",
  "id": "GHSA-c486-5fvq-fp3v",
  "modified": "2026-08-19T12:32:21Z",
  "published": "2026-08-06T18:30:49Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/rrrene/html_sanitize_ex/security/advisories/GHSA-2c6f-3j54-xpcr"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-66829"
    },
    {
      "type": "WEB",
      "url": "https://github.com/rrrene/html_sanitize_ex/commit/29454dc99513fd9b5b6429ab7b6695ad09889227"
    },
    {
      "type": "WEB",
      "url": "https://github.com/rrrene/html_sanitize_ex/commit/9f7e38be51edc38f132dfe994f37af5cf5e0e76f"
    },
    {
      "type": "WEB",
      "url": "https://cna.erlef.org/cves/CVE-2026-66829.html"
    },
    {
      "type": "WEB",
      "url": "https://osv.dev/vulnerability/EEF-CVE-2026-66829"
    }
  ],
  "schema_version": "1.4.0",
  "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:P/PR:N/UI:P/VC:N/VI:N/VA:N/SC:N/SI:L/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",
      "type": "CVSS_V4"
    }
  ]
}

CVE-2026-66829 (GCVE-0-2026-66829)

Vulnerability from cvelistv5 – Published: 2026-08-06 14:49 – Updated: 2026-08-19 11:50

Title

html_sanitize_ex HTML5 scrubber keeps attacker-supplied meta refresh, allowing forced cross-origin redirection

Summary

URL Redirection to Untrusted Site ('Open Redirect') vulnerability in the HTML5 scrubber in rrrene html_sanitize_ex allows a remote attacker to force visitors of a page to navigate to a site of the attacker's choosing via a <meta http-equiv="refresh"> element in sanitized HTML. HtmlSanitizeEx.html5/1 keeps attacker-supplied <meta> elements in its output. A meta element acts on the whole document rather than on the fragment it was embedded in, so it can also declare document-wide directives such as Content-Security-Policy. This is not cross-site scripting. Browsers do not navigate a meta refresh to a javascript: URL, so the uppercase JAVASCRIPT: filter bypass yields no script execution and none was demonstrated. This issue affects html_sanitize_ex: from 0.3.1 before 1.4.5 and from 1.5.0-rc.0 before 1.5.3.

Severity

2.3 (Low)


                        
                          CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:N/VI:N/VA:N/SC:N/SI:L/SA:N

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-08-06 15:42 UTC

CWE

CWE-601 - URL Redirection to Untrusted Site ('Open Redirect')

Assigner

EEF mitre root

References

5 references

URL	Tags
https://github.com/rrrene/html_sanitize_ex/securi…	vendor-advisoryrelated
https://cna.erlef.org/cves/CVE-2026-66829.html	related
https://osv.dev/vulnerability/EEF-CVE-2026-66829	related
https://github.com/rrrene/html_sanitize_ex/commit…	patch
https://github.com/rrrene/html_sanitize_ex/commit…	patch

Impacted products

2 products

Vendor	Product	Version
rrrene	html_sanitize_ex	Affected: 0.3.1 , < 1.4.5 (semver) Affected: 1.5.0-rc.0 , < 1.5.3 (semver) cpe:2.3:a:rrrene:html_sanitize_ex::::::::
rrrene	html_sanitize_ex	Affected: 8976d64ea0b77d26093a94a43ec48a3978e8d028 , < * (git) cpe:2.3:a:rrrene:html_sanitize_ex::::::::

Credits

Peter Ullrich Jonatan Männchen / EEF René Föhring

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-66829",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-08-06T15:42:40.366099Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-08-06T15:42:46.200Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "collectionURL": "https://repo.hex.pm",
          "cpes": [
            "cpe:2.3:a:rrrene:html_sanitize_ex:*:*:*:*:*:*:*:*"
          ],
          "defaultStatus": "unaffected",
          "modules": [
            "Elixir.HtmlSanitizeEx.Scrubber.HTML5",
            "Elixir.HtmlSanitizeEx"
          ],
          "packageName": "html_sanitize_ex",
          "packageURL": "pkg:hex/html_sanitize_ex",
          "product": "html_sanitize_ex",
          "programFiles": [
            "lib/html_sanitize_ex/scrubber/html5.ex",
            "lib/html_sanitize_ex.ex"
          ],
          "programRoutines": [
            {
              "name": "\u0027Elixir.HtmlSanitizeEx.Scrubber.HTML5\u0027:scrub_attribute/2"
            },
            {
              "name": "\u0027Elixir.HtmlSanitizeEx.Scrubber.HTML5\u0027:sanitize/1"
            },
            {
              "name": "\u0027Elixir.HtmlSanitizeEx\u0027:html5/1"
            }
          ],
          "repo": "https://github.com/rrrene/html_sanitize_ex",
          "vendor": "rrrene",
          "versions": [
            {
              "lessThan": "1.4.5",
              "status": "affected",
              "version": "0.3.1",
              "versionType": "semver"
            },
            {
              "lessThan": "1.5.3",
              "status": "affected",
              "version": "1.5.0-rc.0",
              "versionType": "semver"
            }
          ]
        },
        {
          "collectionURL": "https://github.com",
          "cpes": [
            "cpe:2.3:a:rrrene:html_sanitize_ex:*:*:*:*:*:*:*:*"
          ],
          "defaultStatus": "unaffected",
          "modules": [
            "Elixir.HtmlSanitizeEx.Scrubber.HTML5",
            "Elixir.HtmlSanitizeEx"
          ],
          "packageName": "rrrene/html_sanitize_ex",
          "packageURL": "pkg:github/rrrene/html_sanitize_ex",
          "product": "html_sanitize_ex",
          "programFiles": [
            "lib/html_sanitize_ex/scrubber/html5.ex",
            "lib/html_sanitize_ex.ex"
          ],
          "programRoutines": [
            {
              "name": "\u0027Elixir.HtmlSanitizeEx.Scrubber.HTML5\u0027:scrub_attribute/2"
            },
            {
              "name": "\u0027Elixir.HtmlSanitizeEx.Scrubber.HTML5\u0027:sanitize/1"
            },
            {
              "name": "\u0027Elixir.HtmlSanitizeEx\u0027:html5/1"
            }
          ],
          "repo": "https://github.com/rrrene/html_sanitize_ex",
          "vendor": "rrrene",
          "versions": [
            {
              "changes": [
                {
                  "at": "9f7e38be51edc38f132dfe994f37af5cf5e0e76f",
                  "status": "unaffected"
                },
                {
                  "at": "29454dc99513fd9b5b6429ab7b6695ad09889227",
                  "status": "unaffected"
                }
              ],
              "lessThan": "*",
              "status": "affected",
              "version": "8976d64ea0b77d26093a94a43ec48a3978e8d028",
              "versionType": "git"
            }
          ]
        }
      ],
      "configurations": [
        {
          "lang": "en",
          "supportingMedia": [
            {
              "base64": false,
              "type": "text/html",
              "value": "\u003cp\u003eOnly \u003ccode\u003eHtmlSanitizeEx.html5/1\u003c/code\u003e, and custom scrubbers declared with \u003ccode\u003euse HtmlSanitizeEx, extend: :html5\u003c/code\u003e, allow the \u003ccode\u003emeta\u003c/code\u003e element, and the sanitized output must be rendered to other users.\u003c/p\u003e"
            },
            {
              "base64": false,
              "type": "text/markdown",
              "value": "Only `HtmlSanitizeEx.html5/1`, and custom scrubbers declared with `use HtmlSanitizeEx, extend: :html5`, allow the `meta` element, and the sanitized output must be rendered to other users."
            }
          ],
          "value": "Only HtmlSanitizeEx.html5/1, and custom scrubbers declared with use HtmlSanitizeEx, extend: :html5, allow the meta element, and the sanitized output must be rendered to other users."
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:a:rrrene:html_sanitize_ex:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "1.4.5",
                  "versionStartIncluding": "0.3.1",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:a:rrrene:html_sanitize_ex:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "1.5.3",
                  "versionStartIncluding": "1.5.0-rc.0",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ],
          "operator": "AND"
        }
      ],
      "credits": [
        {
          "lang": "en",
          "type": "finder",
          "value": "Peter Ullrich"
        },
        {
          "lang": "en",
          "type": "analyst",
          "value": "Jonatan M\u00e4nnchen / EEF"
        },
        {
          "lang": "en",
          "type": "remediation developer",
          "value": "Ren\u00e9 F\u00f6hring"
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "supportingMedia": [
            {
              "base64": false,
              "type": "text/html",
              "value": "\u003cp\u003eURL Redirection to Untrusted Site (\u0027Open Redirect\u0027) vulnerability in the HTML5 scrubber in rrrene html_sanitize_ex allows a remote attacker to force visitors of a page to navigate to a site of the attacker\u0027s choosing via a \u003ccode\u003e\u0026lt;meta http-equiv=\"refresh\"\u0026gt;\u003c/code\u003e element in sanitized HTML. \u003ccode\u003eHtmlSanitizeEx.html5/1\u003c/code\u003e keeps attacker-supplied \u003ccode\u003e\u0026lt;meta\u0026gt;\u003c/code\u003e elements in its output. A \u003ccode\u003emeta\u003c/code\u003e element acts on the whole document rather than on the fragment it was embedded in, so it can also declare document-wide directives such as \u003ccode\u003eContent-Security-Policy\u003c/code\u003e.\u003c/p\u003e\n\u003cp\u003eThis is not cross-site scripting. Browsers do not navigate a meta refresh to a \u003ccode\u003ejavascript:\u003c/code\u003e URL, so the uppercase \u003ccode\u003eJAVASCRIPT:\u003c/code\u003e filter bypass yields no script execution and none was demonstrated.\u003c/p\u003e\n\u003cp\u003eThis issue affects html_sanitize_ex: from 0.3.1 before 1.4.5 and from 1.5.0-rc.0 before 1.5.3.\u003c/p\u003e"
            },
            {
              "base64": false,
              "type": "text/markdown",
              "value": "URL Redirection to Untrusted Site (\u0027Open Redirect\u0027) vulnerability in the HTML5 scrubber in rrrene html_sanitize_ex allows a remote attacker to force visitors of a page to navigate to a site of the attacker\u0027s choosing via a `\u003cmeta http-equiv=\"refresh\"\u003e` element in sanitized HTML. `HtmlSanitizeEx.html5/1` keeps attacker-supplied `\u003cmeta\u003e` elements in its output. A `meta` element acts on the whole document rather than on the fragment it was embedded in, so it can also declare document-wide directives such as `Content-Security-Policy`.\n\nThis is not cross-site scripting. Browsers do not navigate a meta refresh to a `javascript:` URL, so the uppercase `JAVASCRIPT:` filter bypass yields no script execution and none was demonstrated.\n\nThis issue affects html_sanitize_ex: from 0.3.1 before 1.4.5 and from 1.5.0-rc.0 before 1.5.3."
            }
          ],
          "value": "URL Redirection to Untrusted Site (\u0027Open Redirect\u0027) vulnerability in the HTML5 scrubber in rrrene html_sanitize_ex allows a remote attacker to force visitors of a page to navigate to a site of the attacker\u0027s choosing via a \u003cmeta http-equiv=\"refresh\"\u003e element in sanitized HTML. HtmlSanitizeEx.html5/1 keeps attacker-supplied \u003cmeta\u003e elements in its output. A meta element acts on the whole document rather than on the fragment it was embedded in, so it can also declare document-wide directives such as Content-Security-Policy.\n\nThis is not cross-site scripting. Browsers do not navigate a meta refresh to a javascript: URL, so the uppercase JAVASCRIPT: filter bypass yields no script execution and none was demonstrated.\n\nThis issue affects html_sanitize_ex: from 0.3.1 before 1.4.5 and from 1.5.0-rc.0 before 1.5.3."
        }
      ],
      "impacts": [
        {
          "capecId": "CAPEC-154",
          "descriptions": [
            {
              "lang": "en",
              "value": "CAPEC-154 Resource Location Spoofing"
            }
          ]
        }
      ],
      "metrics": [
        {
          "cvssV4_0": {
            "Automatable": "NOT_DEFINED",
            "Recovery": "NOT_DEFINED",
            "Safety": "NOT_DEFINED",
            "attackComplexity": "LOW",
            "attackRequirements": "PRESENT",
            "attackVector": "NETWORK",
            "baseScore": 2.3,
            "baseSeverity": "LOW",
            "privilegesRequired": "NONE",
            "providerUrgency": "NOT_DEFINED",
            "subAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "NONE",
            "subIntegrityImpact": "LOW",
            "userInteraction": "PASSIVE",
            "valueDensity": "NOT_DEFINED",
            "vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:N/VI:N/VA:N/SC:N/SI:L/SA:N",
            "version": "4.0",
            "vulnAvailabilityImpact": "NONE",
            "vulnConfidentialityImpact": "NONE",
            "vulnIntegrityImpact": "NONE",
            "vulnerabilityResponseEffort": "NOT_DEFINED"
          },
          "format": "CVSS",
          "scenarios": [
            {
              "lang": "en",
              "value": "GENERAL"
            }
          ]
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-601",
              "description": "CWE-601 URL Redirection to Untrusted Site (\u0027Open Redirect\u0027)",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-19T11:50:39.885Z",
        "orgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
        "shortName": "EEF"
      },
      "references": [
        {
          "tags": [
            "vendor-advisory",
            "related"
          ],
          "url": "https://github.com/rrrene/html_sanitize_ex/security/advisories/GHSA-2c6f-3j54-xpcr"
        },
        {
          "tags": [
            "related"
          ],
          "url": "https://cna.erlef.org/cves/CVE-2026-66829.html"
        },
        {
          "tags": [
            "related"
          ],
          "url": "https://osv.dev/vulnerability/EEF-CVE-2026-66829"
        },
        {
          "tags": [
            "patch"
          ],
          "url": "https://github.com/rrrene/html_sanitize_ex/commit/9f7e38be51edc38f132dfe994f37af5cf5e0e76f"
        },
        {
          "tags": [
            "patch"
          ],
          "url": "https://github.com/rrrene/html_sanitize_ex/commit/29454dc99513fd9b5b6429ab7b6695ad09889227"
        }
      ],
      "source": {
        "discovery": "EXTERNAL"
      },
      "title": "html_sanitize_ex HTML5 scrubber keeps attacker-supplied meta refresh, allowing forced cross-origin redirection",
      "workarounds": [
        {
          "lang": "en",
          "supportingMedia": [
            {
              "base64": false,
              "type": "text/html",
              "value": "\u003cp\u003eSanitize with \u003ccode\u003ebasic_html/1\u003c/code\u003e, \u003ccode\u003emarkdown_html/1\u003c/code\u003e or \u003ccode\u003estrip_tags/1\u003c/code\u003e, none of which allow \u003ccode\u003emeta\u003c/code\u003e, or define a custom scrubber that omits it.\u003c/p\u003e"
            },
            {
              "base64": false,
              "type": "text/markdown",
              "value": "Sanitize with `basic_html/1`, `markdown_html/1` or `strip_tags/1`, none of which allow `meta`, or define a custom scrubber that omits it."
            }
          ],
          "value": "Sanitize with basic_html/1, markdown_html/1 or strip_tags/1, none of which allow meta, or define a custom scrubber that omits it."
        }
      ]
    }
  },
  "cveMetadata": {
    "assignerOrgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
    "assignerShortName": "EEF",
    "cveId": "CVE-2026-66829",
    "datePublished": "2026-08-06T14:49:23.468Z",
    "dateReserved": "2026-08-06T08:15:02.719Z",
    "dateUpdated": "2026-08-19T11:50:39.885Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

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.