CVE-2026-71488
HIGHDescription
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.
How to fix
No published remediation has been found for this vulnerability's affected products yet.
Mitigation guidance may be in the linked vendor advisories in the References section below.
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CVSS v3 Vector
Exploitability
Impact
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Exploit Intelligence
Low risk: more likely to be exploited than 27% of all known CVEs.
References
Related Vulnerabilities
Other CWE-407 vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2020-27223 | Medium | 5.2 | 78% | - | Fix |
| CVE-2022-36021 | Medium | 5.5 | 60% | - | Fix |
| CVE-2021-33582 | High | 7.5 | 3.1% | - | Fix |
| CVE-2024-43485 | High | 7.5 | 3.1% | - | Fix |
| CVE-2024-43484 | High | 7.5 | 2.9% | - | Fix |
| CVE-2016-10396 | High | 7.5 | 2.9% | - | - |
Common questions
How do I fix CVE-2026-71488?
No published fix for CVE-2026-71488 has been found yet. Check the linked vendor advisories for guidance as it becomes available.
Is CVE-2026-71488 being actively exploited?
Not that we know of. CVE-2026-71488 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.35% is the estimated probability that it will be exploited in the next 30 days. That is higher than 27% of all scored CVEs.
How severe is CVE-2026-71488?
CVE-2026-71488 has a CVSS v3 base score of 7.5, rated high. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-08-07.