{
"document": {
"category": "csaf_base",
"csaf_version": "2.0",
"distribution": {
"tlp": {
"label": "WHITE"
}
},
"lang": "en",
"notes": [
{
"category": "legal_disclaimer",
"text": "The Netherlands Cyber Security Center (henceforth: NCSC-NL) maintains this portal to enhance access to its information and vulnerabilities. The use of this information is subject to the following terms and conditions:\n\nThe vulnerabilities disclosed in this portal are gathered by NCSC-NL from a variety of open sources, which the user can retrieve from other platforms. NCSC-NL makes every reasonable effort to ensure that the content of this portal is kept up to date, and that it is accurate and complete. Nevertheless, NCSC-NL cannot entirely rule out the possibility of errors, and therefore cannot give any warranty in respect of its completeness, accuracy or real-time keeping up-to-date. NCSC-NL does not control nor guarantee the accuracy, relevance, timeliness or completeness of information obtained from these external sources. The vulnerabilities disclosed in this portal are intended solely for the convenience of professional parties to take appropriate measures to manage the risks posed to the cybersecurity. No rights can be derived from the information provided therein.\n\nNCSC-NL and the Kingdom of the Netherlands assume no legal liability or responsibility for any damage resulting from either the use or inability of use of the vulnerabilities disclosed in this portal. This includes damage resulting from the inaccuracy of incompleteness of the information contained in it.\nThe information on this page is subject to Dutch law. All disputes related to or arising from the use of this portal regarding the disclosure of vulnerabilities will be submitted to the competent court in The Hague. This choice of means also applies to the court in summary proceedings."
}
],
"publisher": {
"category": "coordinator",
"contact_details": "cert@ncsc.nl",
"name": "National Cyber Security Centre",
"namespace": "https://www.ncsc.nl/"
},
"title": "CVE-2026-28348",
"tracking": {
"current_release_date": "2026-03-27T10:11:46.278343Z",
"generator": {
"date": "2026-02-17T15:00:00Z",
"engine": {
"name": "V.E.L.M.A",
"version": "1.7"
}
},
"id": "CVE-2026-28348",
"initial_release_date": "2026-03-02T19:39:49.704295Z",
"revision_history": [
{
"date": "2026-03-02T19:39:49.704295Z",
"number": "1",
"summary": "CVE created.| Source created.| CVE status created. (valid)| Description created for source.| CVSS created.| References created (3).| CWES updated (1)."
},
{
"date": "2026-03-02T19:39:56.718512Z",
"number": "2",
"summary": "NCSC Score created."
},
{
"date": "2026-03-04T18:38:53.425250Z",
"number": "3",
"summary": "Source created.| CVE status created. (valid)| Description created for source.| CVSS created.| Products connected (12).| Product Identifiers created (11).| References created (2).| CWES updated (1)."
},
{
"date": "2026-03-04T18:39:01.193943Z",
"number": "4",
"summary": "NCSC Score updated."
},
{
"date": "2026-03-05T20:39:03.552146Z",
"number": "5",
"summary": "Source created.| CVE status created. (valid)| Description created for source.| CVSS created.| Products created (1).| References created (2).| CWES updated (1)."
},
{
"date": "2026-03-05T20:39:07.948967Z",
"number": "6",
"summary": "NCSC Score updated."
},
{
"date": "2026-03-05T20:47:18.859217Z",
"number": "7",
"summary": "Source created.| CVE status created. (valid)| Description created for source.| CVSS created.| References created (2).| CWES updated (1)."
},
{
"date": "2026-03-05T20:47:23.819604Z",
"number": "8",
"summary": "NCSC Score updated."
},
{
"date": "2026-03-05T23:39:36.849503Z",
"number": "9",
"summary": "References created (1)."
},
{
"date": "2026-03-06T00:37:26.384470Z",
"number": "10",
"summary": "References created (1)."
},
{
"date": "2026-03-06T14:53:21.095053Z",
"number": "11",
"summary": "Source created.| CVE status created. (valid)| EPSS created."
},
{
"date": "2026-03-06T14:53:23.481497Z",
"number": "12",
"summary": "NCSC Score updated."
},
{
"date": "2026-03-06T18:38:50.192196Z",
"number": "13",
"summary": "Unknown change."
},
{
"date": "2026-03-07T00:46:26.396284Z",
"number": "14",
"summary": "Source created.| CVE status created. (valid)| Description created for source."
},
{
"date": "2026-03-09T21:25:09.623548Z",
"number": "15",
"summary": "Products created (1).| Product Identifiers created (1).| Exploits created (1)."
},
{
"date": "2026-03-09T21:25:15.227162Z",
"number": "16",
"summary": "NCSC Score updated."
},
{
"date": "2026-03-20T09:37:46.856016Z",
"number": "17",
"summary": "Source connected.| CVE status created. (valid)| EPSS created."
},
{
"date": "2026-03-27T10:11:42.966849Z",
"number": "18",
"summary": "Source created.| CVE status created. (valid)| Description created for source.| CVSS created.| Products connected (11).| References created (4).| CWES updated (1)."
}
],
"status": "interim",
"version": "18"
}
},
"product_tree": {
"branches": [
{
"branches": [
{
"branches": [
{
"category": "product_version_range",
"name": "vers:unknown/0.1.0",
"product": {
"name": "vers:unknown/0.1.0",
"product_id": "CSAFPID-5759198",
"product_identification_helper": {
"purl": "pkg:pypi/lxml-html-clean@0.1.0"
}
}
},
{
"category": "product_version_range",
"name": "vers:unknown/0.1.1",
"product": {
"name": "vers:unknown/0.1.1",
"product_id": "CSAFPID-5759199",
"product_identification_helper": {
"purl": "pkg:pypi/lxml-html-clean@0.1.1"
}
}
},
{
"category": "product_version_range",
"name": "vers:unknown/0.2.0",
"product": {
"name": "vers:unknown/0.2.0",
"product_id": "CSAFPID-5759200",
"product_identification_helper": {
"purl": "pkg:pypi/lxml-html-clean@0.2.0"
}
}
},
{
"category": "product_version_range",
"name": "vers:unknown/0.2.1",
"product": {
"name": "vers:unknown/0.2.1",
"product_id": "CSAFPID-5759201",
"product_identification_helper": {
"purl": "pkg:pypi/lxml-html-clean@0.2.1"
}
}
},
{
"category": "product_version_range",
"name": "vers:unknown/0.2.2",
"product": {
"name": "vers:unknown/0.2.2",
"product_id": "CSAFPID-5759202",
"product_identification_helper": {
"purl": "pkg:pypi/lxml-html-clean@0.2.2"
}
}
},
{
"category": "product_version_range",
"name": "vers:unknown/0.3.0",
"product": {
"name": "vers:unknown/0.3.0",
"product_id": "CSAFPID-5759203",
"product_identification_helper": {
"purl": "pkg:pypi/lxml-html-clean@0.3.0"
}
}
},
{
"category": "product_version_range",
"name": "vers:unknown/0.3.1",
"product": {
"name": "vers:unknown/0.3.1",
"product_id": "CSAFPID-5759204",
"product_identification_helper": {
"purl": "pkg:pypi/lxml-html-clean@0.3.1"
}
}
},
{
"category": "product_version_range",
"name": "vers:unknown/0.4.0",
"product": {
"name": "vers:unknown/0.4.0",
"product_id": "CSAFPID-5759205",
"product_identification_helper": {
"purl": "pkg:pypi/lxml-html-clean@0.4.0"
}
}
},
{
"category": "product_version_range",
"name": "vers:unknown/0.4.1",
"product": {
"name": "vers:unknown/0.4.1",
"product_id": "CSAFPID-5759206",
"product_identification_helper": {
"purl": "pkg:pypi/lxml-html-clean@0.4.1"
}
}
},
{
"category": "product_version_range",
"name": "vers:unknown/0.4.2",
"product": {
"name": "vers:unknown/0.4.2",
"product_id": "CSAFPID-5759207",
"product_identification_helper": {
"purl": "pkg:pypi/lxml-html-clean@0.4.2"
}
}
},
{
"category": "product_version_range",
"name": "vers:unknown/0.4.3",
"product": {
"name": "vers:unknown/0.4.3",
"product_id": "CSAFPID-5759208",
"product_identification_helper": {
"purl": "pkg:pypi/lxml-html-clean@0.4.3"
}
}
},
{
"category": "product_version_range",
"name": "vers:unknown/>=0|<0.4.4",
"product": {
"name": "vers:unknown/>=0|<0.4.4",
"product_id": "CSAFPID-5759209"
}
}
],
"category": "product_name",
"name": "lxml-html-clean"
},
{
"branches": [
{
"category": "product_version_range",
"name": "vers:unknown/0.1.0",
"product": {
"name": "vers:unknown/0.1.0",
"product_id": "CSAFPID-3236163",
"product_identification_helper": {
"purl": "pkg:pypi/lxml-html-clean@0.1.0"
}
}
},
{
"category": "product_version_range",
"name": "vers:unknown/0.1.1",
"product": {
"name": "vers:unknown/0.1.1",
"product_id": "CSAFPID-3236164",
"product_identification_helper": {
"purl": "pkg:pypi/lxml-html-clean@0.1.1"
}
}
},
{
"category": "product_version_range",
"name": "vers:unknown/0.2.0",
"product": {
"name": "vers:unknown/0.2.0",
"product_id": "CSAFPID-3236165",
"product_identification_helper": {
"purl": "pkg:pypi/lxml-html-clean@0.2.0"
}
}
},
{
"category": "product_version_range",
"name": "vers:unknown/0.2.1",
"product": {
"name": "vers:unknown/0.2.1",
"product_id": "CSAFPID-3236166",
"product_identification_helper": {
"purl": "pkg:pypi/lxml-html-clean@0.2.1"
}
}
},
{
"category": "product_version_range",
"name": "vers:unknown/0.2.2",
"product": {
"name": "vers:unknown/0.2.2",
"product_id": "CSAFPID-3236167",
"product_identification_helper": {
"purl": "pkg:pypi/lxml-html-clean@0.2.2"
}
}
},
{
"category": "product_version_range",
"name": "vers:unknown/0.3.0",
"product": {
"name": "vers:unknown/0.3.0",
"product_id": "CSAFPID-3236168",
"product_identification_helper": {
"purl": "pkg:pypi/lxml-html-clean@0.3.0"
}
}
},
{
"category": "product_version_range",
"name": "vers:unknown/0.3.1",
"product": {
"name": "vers:unknown/0.3.1",
"product_id": "CSAFPID-3236169",
"product_identification_helper": {
"purl": "pkg:pypi/lxml-html-clean@0.3.1"
}
}
},
{
"category": "product_version_range",
"name": "vers:unknown/0.4.0",
"product": {
"name": "vers:unknown/0.4.0",
"product_id": "CSAFPID-5925444"
}
},
{
"category": "product_version_range",
"name": "vers:unknown/0.4.1",
"product": {
"name": "vers:unknown/0.4.1",
"product_id": "CSAFPID-5925445"
}
},
{
"category": "product_version_range",
"name": "vers:unknown/0.4.2",
"product": {
"name": "vers:unknown/0.4.2",
"product_id": "CSAFPID-5925446"
}
},
{
"category": "product_version_range",
"name": "vers:unknown/0.4.3",
"product": {
"name": "vers:unknown/0.4.3",
"product_id": "CSAFPID-5925447"
}
},
{
"category": "product_version_range",
"name": "vers:unknown/<0.4.4",
"product": {
"name": "vers:unknown/<0.4.4",
"product_id": "CSAFPID-5763853"
}
}
],
"category": "product_name",
"name": "lxml_html_clean"
}
],
"category": "vendor",
"name": "fedora-python"
},
{
"branches": [
{
"branches": [
{
"category": "product_version_range",
"name": "vers:unknown/<0.4.4",
"product": {
"name": "vers:unknown/<0.4.4",
"product_id": "CSAFPID-5772478",
"product_identification_helper": {
"cpe": "cpe:2.3:a:fedoralovespython:lxml_html_clean:*:*:*:*:*:python:*:*"
}
}
}
],
"category": "product_name",
"name": "lxml_html_clean"
}
],
"category": "vendor",
"name": "fedoralovespython"
}
]
},
"vulnerabilities": [
{
"cve": "CVE-2026-28348",
"cwe": {
"id": "CWE-116",
"name": "Improper Encoding or Escaping of Output"
},
"notes": [
{
"category": "description",
"text": "### Summary\nThe `_has_sneaky_javascript()` method strips backslashes before checking for dangerous CSS keywords. This causes CSS Unicode escape sequences to bypass the `@import` and `expression()` filters, allowing external CSS loading or XSS in older browsers.\n\n### Details\nThe root cause is located in `clean.py` (around line 594):\n```python\nstyle = style.replace('\\\\', '')\n```\nThis transformation changes a payload like `@\\69mport` into `@69mport`. This resulting string does NOT match the blacklist keyword `@import`. However, all modern browsers' CSS parsers decode `\\69` as the character 'i' (hex 69) according to CSS spec section 4.3.7, interpreting `@\\69mport` as a valid `@import` statement.\n\nSame root cause bypasses `expression()` detection: `\\65xpression(alert(1))` passes through (IE only).\n\n### PoC\n```python\nfrom lxml_html_clean import clean_html\n\n# Normal @import is correctly blocked:\n# clean_html('')\n# Output: \n\n# Unicode escape bypass:\nresult = clean_html('')\nprint(result)\n# Output: \n```\nIf rendered in a browser, the browser loads the external CSS. Variants like `@\\0069mport`, `@\\69 mport` (trailing space), and `@\\49mport` (uppercase I) also work.\n\n### Impact\nExternal CSS loading enables data exfiltration via attribute selectors (e.g., reading CSRF tokens), UI redressing, and phishing. In older browsers (IE), this allows for full XSS via `expression()`.",
"title": "github - https://github.com/advisories/GHSA-hw26-mmpg-fqfg"
},
{
"category": "description",
"text": "### Summary\nThe `_has_sneaky_javascript()` method strips backslashes before checking for dangerous CSS keywords. This causes CSS Unicode escape sequences to bypass the `@import` and `expression()` filters, allowing external CSS loading or XSS in older browsers.\n\n### Details\nThe root cause is located in `clean.py` (around line 594):\n```python\nstyle = style.replace('\\\\', '')\n```\nThis transformation changes a payload like `@\\69mport` into `@69mport`. This resulting string does NOT match the blacklist keyword `@import`. However, all modern browsers' CSS parsers decode `\\69` as the character 'i' (hex 69) according to CSS spec section 4.3.7, interpreting `@\\69mport` as a valid `@import` statement.\n\nSame root cause bypasses `expression()` detection: `\\65xpression(alert(1))` passes through (IE only).\n\n### PoC\n```python\nfrom lxml_html_clean import clean_html\n\n# Normal @import is correctly blocked:\n# clean_html('')\n# Output: \n\n# Unicode escape bypass:\nresult = clean_html('')\nprint(result)\n# Output: \n```\nIf rendered in a browser, the browser loads the external CSS. Variants like `@\\0069mport`, `@\\69 mport` (trailing space), and `@\\49mport` (uppercase I) also work.\n\n### Impact\nExternal CSS loading enables data exfiltration via attribute selectors (e.g., reading CSRF tokens), UI redressing, and phishing. In older browsers (IE), this allows for full XSS via `expression()`.",
"title": "osv - https://www.googleapis.com/download/storage/v1/b/osv-vulnerabilities/o/PyPI%2FGHSA-hw26-mmpg-fqfg.json?alt=media"
},
{
"category": "description",
"text": "lxml_html_clean is a project for HTML cleaning functionalities copied from `lxml.html.clean`. Prior to version 0.4.4, the _has_sneaky_javascript() method strips backslashes before checking for dangerous CSS keywords. This causes CSS Unicode escape sequences to bypass the @import and expression() filters, allowing external CSS loading or XSS in older browsers. This issue has been patched in version 0.4.4.",
"title": "cveprojectv5 - https://www.cve.org/CVERecord?id=CVE-2026-28348"
},
{
"category": "description",
"text": "lxml_html_clean is a project for HTML cleaning functionalities copied from `lxml.html.clean`. Prior to version 0.4.4, the _has_sneaky_javascript() method strips backslashes before checking for dangerous CSS keywords. This causes CSS Unicode escape sequences to bypass the @import and expression() filters, allowing external CSS loading or XSS in older browsers. This issue has been patched in version 0.4.4.",
"title": "nvd - https://nvd.nist.gov/vuln/detail/CVE-2026-28348"
},
{
"category": "description",
"text": "lxml_html_clean is a project for HTML cleaning functionalities copied from `lxml.html.clean`. Prior to version 0.4.4, the _has_sneaky_javascript() method strips backslashes before checking for dangerous CSS keywords. This causes CSS Unicode escape sequences to bypass the @import and expression() filters, allowing external CSS loading or XSS in older browsers. This issue has been patched in version 0.4.4.",
"title": "debian - https://security-tracker.debian.org/tracker/CVE-2026-28348"
},
{
"category": "description",
"text": "lxml_html_clean is a project for HTML cleaning functionalities copied from `lxml.html.clean`. Prior to version 0.4.4, the _has_sneaky_javascript() method strips backslashes before checking for dangerous CSS keywords. This causes CSS Unicode escape sequences to bypass the @import and expression() filters, allowing external CSS loading or XSS in older browsers. This issue has been patched in version 0.4.4.",
"title": "osv - https://www.googleapis.com/download/storage/v1/b/osv-vulnerabilities/o/GIT%2FCVE-2026-28348.json?alt=media"
},
{
"category": "other",
"text": "0.0003",
"title": "EPSS"
},
{
"category": "other",
"text": "3.9",
"title": "NCSC Score"
},
{
"category": "other",
"text": "Is related to CWE-116 (Improper Encoding or Escaping of Output)",
"title": "NCSC Score top increasing factors"
},
{
"category": "other",
"text": "There is exploit data available from source Nvd",
"title": "NCSC Score top decreasing factors"
}
],
"product_status": {
"known_affected": [
"CSAFPID-5759198",
"CSAFPID-5759199",
"CSAFPID-5759200",
"CSAFPID-5759201",
"CSAFPID-5759202",
"CSAFPID-5759203",
"CSAFPID-5759204",
"CSAFPID-5759205",
"CSAFPID-5759206",
"CSAFPID-5759207",
"CSAFPID-5759208",
"CSAFPID-5759209",
"CSAFPID-5763853",
"CSAFPID-5772478",
"CSAFPID-3236163",
"CSAFPID-3236164",
"CSAFPID-3236165",
"CSAFPID-3236166",
"CSAFPID-3236167",
"CSAFPID-3236168",
"CSAFPID-3236169",
"CSAFPID-5925444",
"CSAFPID-5925445",
"CSAFPID-5925446",
"CSAFPID-5925447"
]
},
"references": [
{
"category": "external",
"summary": "Source - github",
"url": "https://github.com/advisories/GHSA-hw26-mmpg-fqfg"
},
{
"category": "external",
"summary": "Source raw - github",
"url": "https://api.github.com/advisories/GHSA-hw26-mmpg-fqfg"
},
{
"category": "external",
"summary": "Source - osv",
"url": "https://www.googleapis.com/download/storage/v1/b/osv-vulnerabilities/o/PyPI%2FGHSA-hw26-mmpg-fqfg.json?alt=media"
},
{
"category": "external",
"summary": "Source - cveprojectv5",
"url": "https://www.cve.org/CVERecord?id=CVE-2026-28348"
},
{
"category": "external",
"summary": "Source raw - cveprojectv5",
"url": "https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2026/28xxx/CVE-2026-28348.json"
},
{
"category": "external",
"summary": "Source - nvd",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-28348"
},
{
"category": "external",
"summary": "Source raw - nvd",
"url": "https://services.nvd.nist.gov/rest/json/cves/2.0?cveId=CVE-2026-28348"
},
{
"category": "external",
"summary": "Source - first",
"url": "https://api.first.org/data/v1/epss?cve=CVE-2026-28348"
},
{
"category": "external",
"summary": "Source raw - first",
"url": "https://api.first.org/data/v1/epss?limit=10000&offset=0"
},
{
"category": "external",
"summary": "Source - debian",
"url": "https://security-tracker.debian.org/tracker/CVE-2026-28348"
},
{
"category": "external",
"summary": "Source - first",
"url": "https://api.first.org/data/v1/epss?limit=10000&offset=0"
},
{
"category": "external",
"summary": "Source - osv",
"url": "https://www.googleapis.com/download/storage/v1/b/osv-vulnerabilities/o/GIT%2FCVE-2026-28348.json?alt=media"
},
{
"category": "external",
"summary": "Reference - cveprojectv5; github; nvd; osv",
"url": "https://github.com/fedora-python/lxml_html_clean/security/advisories/GHSA-hw26-mmpg-fqfg"
},
{
"category": "external",
"summary": "Reference - cveprojectv5; github; nvd; osv",
"url": "https://github.com/fedora-python/lxml_html_clean/commit/2ef732667ddbc74ea59847bcf24b75809aaeed3b"
},
{
"category": "external",
"summary": "Reference - github",
"url": "https://github.com/advisories/GHSA-hw26-mmpg-fqfg"
},
{
"category": "external",
"summary": "Reference - github; osv",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-28348"
},
{
"category": "external",
"summary": "Reference - osv",
"url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/28xxx/CVE-2026-28348.json"
}
],
"scores": [
{
"cvss_v3": {
"version": "3.1",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N",
"baseScore": 6.1,
"baseSeverity": "MEDIUM"
},
"products": [
"CSAFPID-3236163",
"CSAFPID-3236164",
"CSAFPID-3236165",
"CSAFPID-3236166",
"CSAFPID-3236167",
"CSAFPID-3236168",
"CSAFPID-3236169",
"CSAFPID-5759198",
"CSAFPID-5759199",
"CSAFPID-5759200",
"CSAFPID-5759201",
"CSAFPID-5759202",
"CSAFPID-5759203",
"CSAFPID-5759204",
"CSAFPID-5759205",
"CSAFPID-5759206",
"CSAFPID-5759207",
"CSAFPID-5759208",
"CSAFPID-5759209",
"CSAFPID-5763853",
"CSAFPID-5772478",
"CSAFPID-5925444",
"CSAFPID-5925445",
"CSAFPID-5925446",
"CSAFPID-5925447"
]
}
],
"title": "CVE-2026-28348"
}
]
}