High 7.5Published Oct 22, 2026

CVE-2026-115347Mistune before 3.3.0 Quadratic Denial of Service via parse_link_text

Updated under an hour ago (Oct 28, 2026, 12:00 AM ET)

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It affects lepture mistune. Add what you run to find out whether that includes you.

EPSS puts the chance of exploitation in the next 30 days at 0.41%, higher than 35% of scored CVEs.

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Every CVE for lepture mistune

Exploited in the last 30 days

Mistune before 3.3.0 contains an inefficient algorithmic complexity vulnerability in parse_link_text that allows remote attackers to cause denial of service through unbalanced square brackets. Attackers can submit markdown containing long runs of unmatched brackets to mistune.html(), triggering repeated forward scans that stall worker processes for minutes.

CVSS: 7.5 HIGH (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness (CWE): CWE-407
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): 0.41% (percentile 35)
Assigned by: VulnCheck
NVD analysis: Deferred
Record last updated: Oct 26, 2026
First seen by InfoSec Signals: Oct 22, 2026

Affected products

Affected products

lepture mistune lepture:mistune (from the name)	before 3.3.0; 3.3.0 not affected	CNA record

References

References

https://github.com/lepture/mistune/security/advisories/GHSA-f32h-38gf-rg5r	vendor-advisory
https://www.vulncheck.com/advisories/mistune-before-3.3.0-quadratic-denial-of-service-via-parse-link-text	third-party-advisory

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.