🛡️ CVE-2026-71488 on Debian — php-league-commonmark
Description
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.
Distribution advisory
This page covers CVE-2026-71488 as tracked by Debian, for the package php-league-commonmark. The fix is available in version 2.9.0-1; earlier versions remain affected.
How this vulnerability can be exploited
This issue can be reached over the network, attack complexity is low, an attacker needs no privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality none, integrity none, availability high.
Weakness class
DEBIAN-CVE-2026-71488 is classified as CWE-407: Inefficient Algorithmic Complexity. Crafted input drives an algorithm into its worst case, so a small request costs disproportionate work.
Affected software
DEBIAN-CVE-2026-71488 is recorded against 1 package.
- php-league-commonmark (fixed in 2.9.0-1)
Timeline and source
Published on 6 August 2026 and last revised on 11 August 2026. No public exploit is currently recorded for this entry. Record sourced from OSV.
References
Details
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Affected Packages
| Software | From version | Fixed in |
|---|---|---|
| php-league-commonmark | — | 2.9.0-1 |
References
Similar Threats
- Unknown DEBIAN-CVE-2026-71478
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- Unknown UBUNTU-CVE-2026-33347
- Unknown DEBIAN-CVE-2026-30838
Site Security Check
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