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HIGH

CVE-2026-86430

CVSS v3

7.5

HIGH

EPSS Score

—

exploit probability

CISA KEV

No

known exploited

Exploitation

—

SSVC status

Description

league/commonmark versions before 2.9.1 contain multiple denial of service vulnerabilities in fenced code block detection, reference link label lookup, and emphasis delimiter processing that perform super-linear work on crafted input. Attackers can submit specially crafted Markdown with long backtick runs, nested brackets, or delimiter sequences to consume disproportionate CPU time and prevent legitimate requests from completing.

Technical details

CVSS v3 Vector
3.1
Published
2026-09-07
Last Modified
2026-09-07

Frequently asked questions

What is CVE-2026-86430?

league/commonmark versions before 2.9.1 contain multiple denial of service vulnerabilities in fenced code block detection, reference link label lookup, and emphasis delimiter processing that perform super-linear work on crafted input. Attackers can submit specially crafted Markdown with long backtick runs, nested brackets, or delimiter sequences to consume disproportionate CPU time and prevent legitimate requests from completing.

Is CVE-2026-86430 actively exploited?

Active exploitation of CVE-2026-86430 has not been confirmed. The EPSS score is N/A%, indicating the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2026-86430?

CVE-2026-86430 has a CVSS v3 base score of 7.5 (HIGH severity), with vector string 3.1.

Is CVE-2026-86430 affecting your environment?

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