Rendering denial of service via indirect include cycles
Published Jul 8, 2026 · Updated Jul 8, 2026
Uncontrolled recursion in Lepture Mistune before 3.3.0 allows remote attackers to crash rendering via mutually including Markdown files. The Include directive in src/mistune/directives/include.py compares only the destination and immediate source paths, so an indirect cycle repeatedly invokes block.parse until an uncaught RecursionError escapes. The application must enable Include and render attacker-writable files; each trigger fails the rendering request, and repeated triggers interrupt dependent service.
Summary
What happened
Uncontrolled recursion in Lepture Mistune before 3.3.0 allows remote attackers to crash rendering via mutually including Markdown files. The Include directive in src/mistune/directives/include.py compares only the destination and immediate source paths, so an indirect cycle repeatedly invokes block.parse until an uncaught RecursionError escapes. The application must enable Include and render attacker-writable files; each trigger fails the rendering request, and repeated triggers interrupt dependent service.
The record
- CVE
- CVE-2026-59927
- Published
- Jul 8, 2026
- Updated
- Jul 8, 2026
- Vendor
- Lepture
- Product
- Mistune
- Classifications
- CWE-674, CWE-755, T1499.004
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jul 8, 2026CVE publishedPublication date reported by the CVE source.
- Jul 8, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
Compare your product and version with the public record. A matching version still requires validation against your environment.
Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=< 3.3.0
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- GHSA-8mpj-m6qm-5qr8 proof of conceptproof of concept · demonstrated
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
See the directory against your own environment.
Your stack
Check the software in your environment
Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.
Book a demo