CVE-2026-66829 (GCVE-0-2026-66829)
Vulnerability from cvelistv5 – Published: 2026-08-06 14:49 – Updated: 2026-08-19 11:50
VLAI
EPSS
VEX
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
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
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 | CPE status | |
|---|---|---|---|---|
| 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:*:*:*:*:*:*:*:* |
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{
"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"
}
]
}
},
"vulnrichment": {
"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": "2026-08-06T15:42:42.992Z",
"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"
}
}
}
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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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