ubuntu-cve-2026-30838
Vulnerability from osv_ubuntu
Published
2026-03-07 16:15
Modified
2026-05-20 15:26
Summary
Details
league/commonmark is a PHP Markdown parser. Prior to version 2.8.1, the DisallowedRawHtml extension can be bypassed by inserting a newline, tab, or other ASCII whitespace character between a disallowed HTML tag name and the closing >. For example, would pass through unfiltered and be rendered as a valid HTML tag by browsers. This is a cross-site scripting (XSS) vector for any application that relies on this extension to sanitize untrusted user input. All applications using the DisallowedRawHtml extension to process untrusted markdown are affected. Applications that use a dedicated HTML sanitizer (such as HTML Purifier) on the rendered output are not affected. This issue has been patched in version 2.8.1.
Severity
6.1 (Medium)
N/A (UNKNOWN)
References
{
"affected": [
{
"ecosystem_specific": {
"availability": "Available with Ubuntu Pro: https://ubuntu.com/pro",
"binaries": [
{
"binary_name": "php-league-commonmark",
"binary_version": "1.3.1-1ubuntu2+esm1"
}
]
},
"package": {
"ecosystem": "Ubuntu:Pro:20.04:LTS",
"name": "php-league-commonmark",
"purl": "pkg:deb/ubuntu/php-league-commonmark@1.3.1-1ubuntu2+esm1?arch=source\u0026distro=esm-apps/focal"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "1.3.1-1ubuntu2+esm1"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"1.1.2-1",
"1.2.0-1",
"1.3.0-1",
"1.3.1-1",
"1.3.1-1ubuntu2"
]
},
{
"ecosystem_specific": {
"availability": "Available with Ubuntu Pro: https://ubuntu.com/pro",
"binaries": [
{
"binary_name": "php-league-commonmark",
"binary_version": "1.6.7-1ubuntu0.1~esm1"
}
]
},
"package": {
"ecosystem": "Ubuntu:Pro:22.04:LTS",
"name": "php-league-commonmark",
"purl": "pkg:deb/ubuntu/php-league-commonmark@1.6.7-1ubuntu0.1~esm1?arch=source\u0026distro=esm-apps/jammy"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "1.6.7-1ubuntu0.1~esm1"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"1.5.7-2build1",
"1.6.6-1build1",
"1.6.7-1"
]
},
{
"ecosystem_specific": {
"availability": "Available with Ubuntu Pro: https://ubuntu.com/pro",
"binaries": [
{
"binary_name": "php-league-commonmark",
"binary_version": "2.4.2-2ubuntu0.1~esm1"
}
]
},
"package": {
"ecosystem": "Ubuntu:Pro:24.04:LTS",
"name": "php-league-commonmark",
"purl": "pkg:deb/ubuntu/php-league-commonmark@2.4.2-2ubuntu0.1~esm1?arch=source\u0026distro=esm-apps/noble"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "2.4.2-2ubuntu0.1~esm1"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"2.3.9-1",
"2.4.1-1",
"2.4.2-1",
"2.4.2-2"
]
},
{
"ecosystem_specific": {
"binaries": [
{
"binary_name": "php-league-commonmark",
"binary_version": "2.7.0-1"
}
]
},
"package": {
"ecosystem": "Ubuntu:25.10",
"name": "php-league-commonmark",
"purl": "pkg:deb/ubuntu/php-league-commonmark@2.7.0-1?arch=source\u0026distro=questing"
},
"ranges": [
{
"events": [
{
"introduced": "0"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"2.6.1-2",
"2.6.2-1",
"2.7.0-1"
]
},
{
"ecosystem_specific": {
"binaries": [
{
"binary_name": "php-league-commonmark",
"binary_version": "2.8.0-1"
}
]
},
"package": {
"ecosystem": "Ubuntu:26.04:LTS",
"name": "php-league-commonmark",
"purl": "pkg:deb/ubuntu/php-league-commonmark@2.8.0-1?arch=source\u0026distro=resolute"
},
"ranges": [
{
"events": [
{
"introduced": "0"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"2.7.0-1",
"2.7.1-2",
"2.8.0-1"
]
}
],
"aliases": [],
"details": "league/commonmark is a PHP Markdown parser. Prior to version 2.8.1, the DisallowedRawHtml extension can be bypassed by inserting a newline, tab, or other ASCII whitespace character between a disallowed HTML tag name and the closing \u003e. For example, \u003cscript\\n\u003e would pass through unfiltered and be rendered as a valid HTML tag by browsers. This is a cross-site scripting (XSS) vector for any application that relies on this extension to sanitize untrusted user input. All applications using the DisallowedRawHtml extension to process untrusted markdown are affected. Applications that use a dedicated HTML sanitizer (such as HTML Purifier) on the rendered output are not affected. This issue has been patched in version 2.8.1.",
"id": "UBUNTU-CVE-2026-30838",
"modified": "2026-05-20T15:26:08Z",
"published": "2026-03-07T16:15:00Z",
"references": [
{
"type": "REPORT",
"url": "https://ubuntu.com/security/CVE-2026-30838"
},
{
"type": "REPORT",
"url": "https://www.cve.org/CVERecord?id=CVE-2026-30838"
},
{
"type": "REPORT",
"url": "https://github.com/thephpleague/commonmark/security/advisories/GHSA-4v6x-c7xx-hw9f"
},
{
"type": "ADVISORY",
"url": "https://ubuntu.com/security/notices/USN-8194-1"
}
],
"related": [
"USN-8194-1"
],
"schema_version": "1.7.0",
"severity": [
{
"score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:N/VI:L/VA:N/SC:L/SI:L/SA:N",
"type": "CVSS_V4"
},
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N",
"type": "CVSS_V3"
},
{
"score": "medium",
"type": "Ubuntu"
}
],
"upstream": [
"CVE-2026-30838"
]
}
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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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