CVE-2026-115348
High
Description
Mistune from 3.0.0 before 3.3.0 contains an algorithmic complexity vulnerability in the inline link parser's parse_link_text function that allows unauthenticated attackers to exhaust CPU with unbalanced brackets. Attackers can submit Markdown containing many unbalanced '[' or '![' characters, forcing repeated unbounded forward scans and tying up worker processes for minutes.
SeverityHigh
CVSS7.5
Exploit probability—
ProductLepture Mistune
PublishedOct 22, 2026
First seenOct 22, 2026
Weakness typeCWE-400Uncontrolled resource consumption
How to fix
Update
- lepture mistune3.3.0 or later
Vendor advisories
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| lepture mistune | 3.0.0 ≤ v < 3.3.0 | 3.3.0 |
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