6.1
MEDIUM
CVSS 3.1
CVE-2026-66829
html_sanitize_ex HTML5 scrubber keeps attacker-supplied meta refresh, allowing forced cross-origin redirection
Overview
Description
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.
Details
INFO
Published Date :
Aug. 6, 2026, 4:16 p.m.
Last Modified :
Oct. 24, 2026, 4:10 p.m.
Remotely Exploit :
Yes !
Source :
6b3ad84c-e1a6-4bf7-a703-f496b71e49db
Impact
Affected Products
The following products are affected by CVE-2026-66829
vulnerability.
Even if cvefeed.io is aware of the exact versions of the
products
that
are
affected, the information is not represented in the table below.
Scoring
CVSS Scores
The Common Vulnerability Scoring System is a standardized framework
for assessing the severity of vulnerabilities in software and systems.
We collect and displays CVSS scores from various sources for each CVE.
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | MEDIUM | [email protected] | ||||
| CVSS 4.0 | LOW | 6b3ad84c-e1a6-4bf7-a703-f496b71e49db | ||||
| CVSS 4.0 | LOW | 6b3ad84c-e1a6-4bf7-a703-f496b71e49db |
Solution
Update the HTML sanitizer library to a patched version to prevent redirection to malicious sites.
- Update html_sanitize_ex to version 1.5.3 or later.
- Review and sanitize all user-supplied HTML input.
- Implement strict validation for meta tag content.
References
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-66829.
| URL | Resource |
|---|---|
| https://cna.erlef.org/cves/CVE-2026-66829.html | Patch Third Party Advisory |
| https://github.com/rrrene/html_sanitize_ex/commit/29454dc99513fd9b5b6429ab7b6695ad09889227 | |
| https://github.com/rrrene/html_sanitize_ex/commit/9f7e38be51edc38f132dfe994f37af5cf5e0e76f | Patch |
| https://github.com/rrrene/html_sanitize_ex/security/advisories/GHSA-2c6f-3j54-xpcr | Broken Link |
| https://osv.dev/vulnerability/EEF-CVE-2026-66829 | Patch Third Party Advisory |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-66829 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-66829
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-66829 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-66829 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
CVE Translated by [email protected]
Oct. 24, 2026
Action Type Old Value New Value Changed Translation Title: html_sanitize_ex de rrrene, Description: La vulnerabilidad de redirección de URL a sitio no confiable (’redirección abierta’) en el depurador HTML5 de rrrene html_sanitize_ex permite a un atacante remoto forzar a los visitantes de una página a navegar a un sitio elegido por el atacante a través de un elemento <meta http-equiv=“refresh”> en HTML saneado. HtmlSanitizeEx.html5/1 mantiene los elementos [meta] proporcionados por el atacante en su salida. Un elemento meta actúa sobre todo el documento en lugar de sobre el fragmento en el que fue incrustado, por lo que también puede declarar directivas a nivel de documento como Content-Security-Policy. Esto no es cross-site scripting. Los navegadores no navegan una meta refresh a una URL javascript_disabled: , por lo que el bypass del filtro javascript_disabled: en mayúsculas no produce ejecución de script y no se demostró ninguna. Este problema afecta a html_sanitize_ex: desde 0.3.1 antes de 1.5.3. Title: html_sanitize_ex de rrrene, Description: La vulnerabilidad de redirección de URL a sitio no confiable (’redirección abierta’) en el depurador HTML5 de rrrene html_sanitize_ex permite a un atacante remoto forzar a los visitantes de una página a navegar a un sitio elegido por el atacante a través de un elemento menor quemeta http-equiv=“refresh”mayor que en HTML saneado. HtmlSanitizeEx.html5/1 mantiene los elementos [meta] proporcionados por el atacante en su salida. Un elemento meta actúa sobre todo el documento en lugar de sobre el fragmento en el que fue incrustado, por lo que también puede declarar directivas a nivel de documento como Content-Security-Policy. Esto no es cross-site scripting. Los navegadores no navegan una meta refresh a una URL javascript_disabled: , por lo que el bypass del filtro javascript_disabled: en mayúsculas no produce ejecución de script y no se demostró ninguna. Este problema afecta a html_sanitize_ex: desde 0.3.1 antes de 1.5.3. -
CVE Translated by [email protected]
Oct. 23, 2026
Action Type Old Value New Value Added Translation Title: html_sanitize_ex de rrrene, Description: La vulnerabilidad de redirección de URL a sitio no confiable (’redirección abierta’) en el depurador HTML5 de rrrene html_sanitize_ex permite a un atacante remoto forzar a los visitantes de una página a navegar a un sitio elegido por el atacante a través de un elemento <meta http-equiv=“refresh”> en HTML saneado. HtmlSanitizeEx.html5/1 mantiene los elementos [meta] proporcionados por el atacante en su salida. Un elemento meta actúa sobre todo el documento en lugar de sobre el fragmento en el que fue incrustado, por lo que también puede declarar directivas a nivel de documento como Content-Security-Policy. Esto no es cross-site scripting. Los navegadores no navegan una meta refresh a una URL javascript_disabled: , por lo que el bypass del filtro javascript_disabled: en mayúsculas no produce ejecución de script y no se demostró ninguna. Este problema afecta a html_sanitize_ex: desde 0.3.1 antes de 1.5.3. -
CVE Modified by 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
Aug. 19, 2026
Action Type Old Value New Value Changed Affected [{'cpes': ['cpe:2.3:a:rrrene:html_sanitize_ex:*:*:*:*:*:*:*:*'], 'repo': 'https://github.com/rrrene/html_sanitize_ex', 'vendor': 'rrrene', 'modules': ['Elixir.HtmlSanitizeEx.Scrubber.HTML5', 'Elixir.HtmlSanitizeEx'], 'product': 'html_sanitize_ex', 'versions': [{'status': 'affected', 'version': '0.3.1', 'lessThan': '1.5.3', 'versionType': 'semver'}], 'packageURL': 'pkg:hex/html_sanitize_ex', 'packageName': 'html_sanitize_ex', 'programFiles': ['lib/html_sanitize_ex/scrubber/html5.ex', 'lib/html_sanitize_ex.ex'], 'collectionURL': 'https://repo.hex.pm', 'defaultStatus': 'unaffected', 'programRoutines': [{'name': "'Elixir.HtmlSanitizeEx.Scrubber.HTML5':scrub_attribute/2"}, {'name': "'Elixir.HtmlSanitizeEx.Scrubber.HTML5':sanitize/1"}, {'name': "'Elixir.HtmlSanitizeEx':html5/1"}]}, {'cpes': ['cpe:2.3:a:rrrene:html_sanitize_ex:*:*:*:*:*:*:*:*'], 'repo': 'https://github.com/rrrene/html_sanitize_ex', 'vendor': 'rrrene', 'modules': ['Elixir.HtmlSanitizeEx.Scrubber.HTML5', 'Elixir.HtmlSanitizeEx'], 'product': 'html_sanitize_ex', 'versions': [{'status': 'affected', 'version': '8976d64ea0b77d26093a94a43ec48a3978e8d028', 'lessThan': '9f7e38be51edc38f132dfe994f37af5cf5e0e76f', 'versionType': 'git'}], 'packageURL': 'pkg:github/rrrene/html_sanitize_ex', 'packageName': 'rrrene/html_sanitize_ex', 'programFiles': ['lib/html_sanitize_ex/scrubber/html5.ex', 'lib/html_sanitize_ex.ex'], 'collectionURL': 'https://github.com', 'defaultStatus': 'unaffected', 'programRoutines': [{'name': "'Elixir.HtmlSanitizeEx.Scrubber.HTML5':scrub_attribute/2"}, {'name': "'Elixir.HtmlSanitizeEx.Scrubber.HTML5':sanitize/1"}, {'name': "'Elixir.HtmlSanitizeEx':html5/1"}]}] [{'cpes': ['cpe:2.3:a:rrrene:html_sanitize_ex:*:*:*:*:*:*:*:*'], 'repo': 'https://github.com/rrrene/html_sanitize_ex', 'vendor': 'rrrene', 'modules': ['Elixir.HtmlSanitizeEx.Scrubber.HTML5', 'Elixir.HtmlSanitizeEx'], 'product': 'html_sanitize_ex', 'versions': [{'status': 'affected', 'version': '0.3.1', 'lessThan': '1.4.5', 'versionType': 'semver'}, {'status': 'affected', 'version': '1.5.0-rc.0', 'lessThan': '1.5.3', 'versionType': 'semver'}], 'packageURL': 'pkg:hex/html_sanitize_ex', 'packageName': 'html_sanitize_ex', 'programFiles': ['lib/html_sanitize_ex/scrubber/html5.ex', 'lib/html_sanitize_ex.ex'], 'collectionURL': 'https://repo.hex.pm', 'defaultStatus': 'unaffected', 'programRoutines': [{'name': "'Elixir.HtmlSanitizeEx.Scrubber.HTML5':scrub_attribute/2"}, {'name': "'Elixir.HtmlSanitizeEx.Scrubber.HTML5':sanitize/1"}, {'name': "'Elixir.HtmlSanitizeEx':html5/1"}]}, {'cpes': ['cpe:2.3:a:rrrene:html_sanitize_ex:*:*:*:*:*:*:*:*'], 'repo': 'https://github.com/rrrene/html_sanitize_ex', 'vendor': 'rrrene', 'modules': ['Elixir.HtmlSanitizeEx.Scrubber.HTML5', 'Elixir.HtmlSanitizeEx'], 'product': 'html_sanitize_ex', 'versions': [{'status': 'affected', 'changes': [{'at': '9f7e38be51edc38f132dfe994f37af5cf5e0e76f', 'status': 'unaffected'}, {'at': '29454dc99513fd9b5b6429ab7b6695ad09889227', 'status': 'unaffected'}], 'version': '8976d64ea0b77d26093a94a43ec48a3978e8d028', 'lessThan': '*', 'versionType': 'git'}], 'packageURL': 'pkg:github/rrrene/html_sanitize_ex', 'packageName': 'rrrene/html_sanitize_ex', 'programFiles': ['lib/html_sanitize_ex/scrubber/html5.ex', 'lib/html_sanitize_ex.ex'], 'collectionURL': 'https://github.com', 'defaultStatus': 'unaffected', 'programRoutines': [{'name': "'Elixir.HtmlSanitizeEx.Scrubber.HTML5':scrub_attribute/2"}, {'name': "'Elixir.HtmlSanitizeEx.Scrubber.HTML5':sanitize/1"}, {'name': "'Elixir.HtmlSanitizeEx':html5/1"}]}] Changed Description 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 1.5.3. 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. Added Reference https://github.com/rrrene/html_sanitize_ex/commit/29454dc99513fd9b5b6429ab7b6695ad09889227 -
Initial Analysis by [email protected]
Aug. 11, 2026
Action Type Old Value New Value Added CVSS V3.1 AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N Added CPE Configuration OR *cpe:2.3:a:rrrene:htmlsanitizeex:*:*:*:*:*:*:*:* versions from (including) 0.3.1 up to (excluding) 1.5.3 Added Reference Type EEF: https://cna.erlef.org/cves/CVE-2026-66829.html Types: Patch, Third Party Advisory Added Reference Type EEF: https://github.com/rrrene/html_sanitize_ex/commit/9f7e38be51edc38f132dfe994f37af5cf5e0e76f Types: Patch Added Reference Type EEF: https://github.com/rrrene/html_sanitize_ex/security/advisories/GHSA-2c6f-3j54-xpcr Types: Broken Link Added Reference Type EEF: https://osv.dev/vulnerability/EEF-CVE-2026-66829 Types: Patch, Third Party Advisory -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Aug. 06, 2026
Action Type Old Value New Value Added SSVC {'id': 'CVE-2026-66829', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'no'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-08-06T15:42:40.366099Z'} -
New CVE Received by 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
Aug. 06, 2026
Action Type Old Value New Value Added Affected [{'cpes': ['cpe:2.3:a:rrrene:html_sanitize_ex:*:*:*:*:*:*:*:*'], 'repo': 'https://github.com/rrrene/html_sanitize_ex', 'vendor': 'rrrene', 'modules': ['Elixir.HtmlSanitizeEx.Scrubber.HTML5', 'Elixir.HtmlSanitizeEx'], 'product': 'html_sanitize_ex', 'versions': [{'status': 'affected', 'version': '0.3.1', 'lessThan': '1.5.3', 'versionType': 'semver'}], 'packageURL': 'pkg:hex/html_sanitize_ex', 'packageName': 'html_sanitize_ex', 'programFiles': ['lib/html_sanitize_ex/scrubber/html5.ex', 'lib/html_sanitize_ex.ex'], 'collectionURL': 'https://repo.hex.pm', 'defaultStatus': 'unaffected', 'programRoutines': [{'name': "'Elixir.HtmlSanitizeEx.Scrubber.HTML5':scrub_attribute/2"}, {'name': "'Elixir.HtmlSanitizeEx.Scrubber.HTML5':sanitize/1"}, {'name': "'Elixir.HtmlSanitizeEx':html5/1"}]}, {'cpes': ['cpe:2.3:a:rrrene:html_sanitize_ex:*:*:*:*:*:*:*:*'], 'repo': 'https://github.com/rrrene/html_sanitize_ex', 'vendor': 'rrrene', 'modules': ['Elixir.HtmlSanitizeEx.Scrubber.HTML5', 'Elixir.HtmlSanitizeEx'], 'product': 'html_sanitize_ex', 'versions': [{'status': 'affected', 'version': '8976d64ea0b77d26093a94a43ec48a3978e8d028', 'lessThan': '9f7e38be51edc38f132dfe994f37af5cf5e0e76f', 'versionType': 'git'}], 'packageURL': 'pkg:github/rrrene/html_sanitize_ex', 'packageName': 'rrrene/html_sanitize_ex', 'programFiles': ['lib/html_sanitize_ex/scrubber/html5.ex', 'lib/html_sanitize_ex.ex'], 'collectionURL': 'https://github.com', 'defaultStatus': 'unaffected', 'programRoutines': [{'name': "'Elixir.HtmlSanitizeEx.Scrubber.HTML5':scrub_attribute/2"}, {'name': "'Elixir.HtmlSanitizeEx.Scrubber.HTML5':sanitize/1"}, {'name': "'Elixir.HtmlSanitizeEx':html5/1"}]}] Added Description 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 1.5.3. Added CVSS V4.0 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 Added CWE CWE-601 Added Reference https://cna.erlef.org/cves/CVE-2026-66829.html Added Reference https://github.com/rrrene/html_sanitize_ex/commit/9f7e38be51edc38f132dfe994f37af5cf5e0e76f Added Reference https://github.com/rrrene/html_sanitize_ex/security/advisories/GHSA-2c6f-3j54-xpcr Added Reference https://osv.dev/vulnerability/EEF-CVE-2026-66829
EPSS is a daily estimate of the probability of exploitation activity
being observed over the next 30 days. Following chart shows the EPSS
score history of the vulnerability.