Algorithmic Complexity Affecting php-league-commonmark package, versions *


Severity

Recommended
0.0
high
0
10

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Threat Intelligence

EPSS
0.52% (42nd percentile)

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  • Snyk IDSNYK-ECHOLATEST-PHPLEAGUECOMMONMARK-19643816
  • published8 Sept 2026
  • disclosed7 Sept 2026

Introduced: 7 Sep 2026

CVE-2026-86429  (opens in a new tab)
CWE-407  (opens in a new tab)

How to fix?

There is no fixed version for Echo:latest php-league-commonmark.

NVD Description

Note: Versions mentioned in the description apply only to the upstream php-league-commonmark package and not the php-league-commonmark package as distributed by Echo. See How to fix? for Echo:latest relevant fixed versions and status.

The league/commonmark (thephpleague/commonmark) library in versions >= 1.5.0 and < 2.9.1 contains quadratic parsing complexity in its SmartPunctExtension and AttributesExtension. When either extension is explicitly registered on the Environment (they are not enabled by default and are excluded from the standard CommonMark and GitHub-Flavored Markdown converters), an unauthenticated attacker can submit small, specially crafted Markdown documents — such as text alternating with unpaired quotes, contiguous runs of block-level attribute blocks, or repeated class attributes — to trigger disproportionate CPU consumption and cause a denial of service. Fixed in 2.9.1.

CVSS Base Scores

version 3.1