UBUNTU-CVE-2026-71488 (CVE-2026-71488)
Vulnerability from osv_ubuntu – Published: 2026-08-06 22:18 – Updated: 2026-08-13 00:14 – Source website
VLAI
Details
league/commonmark is a PHP library for parsing and rendering CommonMark Markdown. From 0.6.0 until 2.9.0, specially crafted Markdown lines can cause the parser to have quadratic time complexity when converting, because several parsing paths repeatedly rescan growing portions of a line to translate between character positions and byte positions, and the Autolink extension can also copy and validate the remaining line at every URL-like prefix, allowing an attacker who can submit Markdown for conversion to consume disproportionate CPU time with a comparatively small request. This issue is fixed in 2.9.0.
Severity
7.5 (High)
N/A (UNKNOWN)
References
{
"affected": [
{
"ecosystem_specific": {
"binaries": [
{
"binary_name": "markdown",
"binary_version": "1.0.1-8"
}
]
},
"package": {
"ecosystem": "Ubuntu:16.04:LTS",
"name": "markdown",
"purl": "pkg:deb/ubuntu/markdown@1.0.1-8?arch=source\u0026distro=xenial"
},
"ranges": [
{
"events": [
{
"introduced": "0"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"1.0.1-7",
"1.0.1-8"
]
},
{
"ecosystem_specific": {
"binaries": [
{
"binary_name": "markdown",
"binary_version": "1.0.1-10"
}
]
},
"package": {
"ecosystem": "Ubuntu:18.04:LTS",
"name": "markdown",
"purl": "pkg:deb/ubuntu/markdown@1.0.1-10?arch=source\u0026distro=bionic"
},
"ranges": [
{
"events": [
{
"introduced": "0"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"1.0.1-9",
"1.0.1-10"
]
},
{
"ecosystem_specific": {
"binaries": [
{
"binary_name": "markdown",
"binary_version": "1.0.1-10"
}
]
},
"package": {
"ecosystem": "Ubuntu:20.04:LTS",
"name": "markdown",
"purl": "pkg:deb/ubuntu/markdown@1.0.1-10?arch=source\u0026distro=focal"
},
"ranges": [
{
"events": [
{
"introduced": "0"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"1.0.1-10"
]
},
{
"ecosystem_specific": {
"binaries": [
{
"binary_name": "python3-commonmark",
"binary_version": "0.9.1-3"
}
]
},
"package": {
"ecosystem": "Ubuntu:22.04:LTS",
"name": "commonmark",
"purl": "pkg:deb/ubuntu/commonmark@0.9.1-3?arch=source\u0026distro=jammy"
},
"ranges": [
{
"events": [
{
"introduced": "0"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"0.9.1-3"
]
},
{
"ecosystem_specific": {
"binaries": [
{
"binary_name": "markdown",
"binary_version": "1.0.1-10.1"
}
]
},
"package": {
"ecosystem": "Ubuntu:22.04:LTS",
"name": "markdown",
"purl": "pkg:deb/ubuntu/markdown@1.0.1-10.1?arch=source\u0026distro=jammy"
},
"ranges": [
{
"events": [
{
"introduced": "0"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"1.0.1-10.1"
]
},
{
"ecosystem_specific": {
"binaries": [
{
"binary_name": "python3-commonmark",
"binary_version": "0.9.1-5"
}
]
},
"package": {
"ecosystem": "Ubuntu:24.04:LTS",
"name": "commonmark",
"purl": "pkg:deb/ubuntu/commonmark@0.9.1-5?arch=source\u0026distro=noble"
},
"ranges": [
{
"events": [
{
"introduced": "0"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"0.9.1-4",
"0.9.1-5"
]
},
{
"ecosystem_specific": {
"binaries": [
{
"binary_name": "markdown",
"binary_version": "1.0.1-12"
}
]
},
"package": {
"ecosystem": "Ubuntu:24.04:LTS",
"name": "markdown",
"purl": "pkg:deb/ubuntu/markdown@1.0.1-12?arch=source\u0026distro=noble"
},
"ranges": [
{
"events": [
{
"introduced": "0"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"1.0.1-12"
]
},
{
"ecosystem_specific": {
"binaries": [
{
"binary_name": "python3-commonmark",
"binary_version": "0.9.1-8build1"
}
]
},
"package": {
"ecosystem": "Ubuntu:26.04:LTS",
"name": "commonmark",
"purl": "pkg:deb/ubuntu/commonmark@0.9.1-8build1?arch=source\u0026distro=resolute"
},
"ranges": [
{
"events": [
{
"introduced": "0"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"0.9.1-8",
"0.9.1-8build1"
]
},
{
"ecosystem_specific": {
"binaries": [
{
"binary_name": "markdown",
"binary_version": "1.0.1-14"
}
]
},
"package": {
"ecosystem": "Ubuntu:26.04:LTS",
"name": "markdown",
"purl": "pkg:deb/ubuntu/markdown@1.0.1-14?arch=source\u0026distro=resolute"
},
"ranges": [
{
"events": [
{
"introduced": "0"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"1.0.1-14"
]
}
],
"aliases": [],
"details": "league/commonmark is a PHP library for parsing and rendering CommonMark Markdown. From 0.6.0 until 2.9.0, specially crafted Markdown lines can cause the parser to have quadratic time complexity when converting, because several parsing paths repeatedly rescan growing portions of a line to translate between character positions and byte positions, and the Autolink extension can also copy and validate the remaining line at every URL-like prefix, allowing an attacker who can submit Markdown for conversion to consume disproportionate CPU time with a comparatively small request. This issue is fixed in 2.9.0.",
"id": "UBUNTU-CVE-2026-71488",
"modified": "2026-08-13T00:14:08Z",
"published": "2026-08-06T22:18:00Z",
"references": [
{
"type": "REPORT",
"url": "https://ubuntu.com/security/CVE-2026-71488"
},
{
"type": "REPORT",
"url": "https://www.cve.org/CVERecord?id=CVE-2026-71488"
},
{
"type": "REPORT",
"url": "https://github.com/thephpleague/commonmark/commit/a6ef6cdc308dfa39a34239c35818e75892a0e6a8"
},
{
"type": "REPORT",
"url": "https://github.com/thephpleague/commonmark/commit/a70979ea0d7d3377bd7127536748454a922bf5eb"
},
{
"type": "REPORT",
"url": "https://github.com/thephpleague/commonmark/commit/c97b02e5e652b992033b93ba5d6182f706343fc6"
},
{
"type": "REPORT",
"url": "https://github.com/thephpleague/commonmark/releases/tag/2.9.0"
},
{
"type": "REPORT",
"url": "https://github.com/thephpleague/commonmark/security/advisories/GHSA-2q4p-g7hv-5rgv"
}
],
"related": [],
"schema_version": "1.7.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
},
{
"score": "medium",
"type": "Ubuntu"
}
],
"upstream": [
"CVE-2026-71488"
]
}
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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
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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
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