FKIE_CVE-2026-66829
Vulnerability from fkie_nvd - Published: 2026-08-06 16:16 - Updated: 2026-08-19 12:18
Severity
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.
References
Impacted products
| Vendor | Product | Version | |
|---|---|---|---|
| rrrene | htmlsanitizeex | * |
{
"affected": [
{
"affectedData": [
{
"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"
}
]
}
],
"source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db"
}
],
"configurations": [
{
"nodes": [
{
"cpeMatch": [
{
"criteria": "cpe:2.3:a:rrrene:htmlsanitizeex:*:*:*:*:*:*:*:*",
"matchCriteriaId": "DE85053C-AE84-4570-A90C-4D4CCD7A4BA3",
"versionEndExcluding": "1.5.3",
"versionStartIncluding": "0.3.1",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
]
}
],
"cveTags": [],
"descriptions": [
{
"lang": "en",
"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."
}
],
"id": "CVE-2026-66829",
"lastModified": "2026-08-19T12:18:34.627",
"metrics": {
"cvssMetricV31": [
{
"cvssData": {
"attackComplexity": "LOW",
"attackVector": "NETWORK",
"availabilityImpact": "NONE",
"baseScore": 6.1,
"baseSeverity": "MEDIUM",
"confidentialityImpact": "LOW",
"integrityImpact": "LOW",
"privilegesRequired": "NONE",
"scope": "CHANGED",
"userInteraction": "REQUIRED",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N",
"version": "3.1"
},
"exploitabilityScore": 2.8,
"impactScore": 2.7,
"source": "nvd@nist.gov",
"type": "Primary"
}
],
"cvssMetricV40": [
{
"cvssData": {
"Automatable": "NOT_DEFINED",
"Recovery": "NOT_DEFINED",
"Safety": "NOT_DEFINED",
"attackComplexity": "LOW",
"attackRequirements": "PRESENT",
"attackVector": "NETWORK",
"availabilityRequirement": "NOT_DEFINED",
"baseScore": 2.3,
"baseSeverity": "LOW",
"confidentialityRequirement": "NOT_DEFINED",
"exploitMaturity": "NOT_DEFINED",
"integrityRequirement": "NOT_DEFINED",
"modifiedAttackComplexity": "NOT_DEFINED",
"modifiedAttackRequirements": "NOT_DEFINED",
"modifiedAttackVector": "NOT_DEFINED",
"modifiedPrivilegesRequired": "NOT_DEFINED",
"modifiedSubAvailabilityImpact": "NOT_DEFINED",
"modifiedSubConfidentialityImpact": "NOT_DEFINED",
"modifiedSubIntegrityImpact": "NOT_DEFINED",
"modifiedUserInteraction": "NOT_DEFINED",
"modifiedVulnAvailabilityImpact": "NOT_DEFINED",
"modifiedVulnConfidentialityImpact": "NOT_DEFINED",
"modifiedVulnIntegrityImpact": "NOT_DEFINED",
"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/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",
"version": "4.0",
"vulnAvailabilityImpact": "NONE",
"vulnConfidentialityImpact": "NONE",
"vulnIntegrityImpact": "NONE",
"vulnerabilityResponseEffort": "NOT_DEFINED"
},
"source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
"type": "Secondary"
}
],
"ssvcV203": [
{
"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"ssvcData": {
"id": "CVE-2026-66829",
"options": [
{
"exploitation": "none"
},
{
"automatable": "no"
},
{
"technicalImpact": "partial"
}
],
"role": "CISA Coordinator",
"timestamp": "2026-08-06T15:42:40.366099Z",
"version": "2.0.3"
}
}
]
},
"published": "2026-08-06T16:16:49.450",
"references": [
{
"source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
"tags": [
"Patch",
"Third Party Advisory"
],
"url": "https://cna.erlef.org/cves/CVE-2026-66829.html"
},
{
"source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
"url": "https://github.com/rrrene/html_sanitize_ex/commit/29454dc99513fd9b5b6429ab7b6695ad09889227"
},
{
"source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
"tags": [
"Patch"
],
"url": "https://github.com/rrrene/html_sanitize_ex/commit/9f7e38be51edc38f132dfe994f37af5cf5e0e76f"
},
{
"source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
"tags": [
"Broken Link"
],
"url": "https://github.com/rrrene/html_sanitize_ex/security/advisories/GHSA-2c6f-3j54-xpcr"
},
{
"source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
"tags": [
"Patch",
"Third Party Advisory"
],
"url": "https://osv.dev/vulnerability/EEF-CVE-2026-66829"
}
],
"sourceIdentifier": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
"vulnStatus": "Modified",
"weaknesses": [
{
"description": [
{
"lang": "en",
"value": "CWE-601"
}
],
"source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
"type": "Secondary"
}
]
}
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Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
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.
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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.
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.
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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.
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