Parser crash via null child-token assertions
Published Feb 22, 2023 · Updated Mar 11, 2025
Denial of service in Executable Books markdown-it-py before 2.2.0 allows local users to crash Markdown rendering with crafted input. The renderer assumes inline and image tokens always contain child-token lists and uses assertions instead of accepting an unset list; a malformed nested-image sequence violates that assumption and raises AssertionError. Exploitation requires attacker-controlled Markdown to reach an affected parser process, and the bounded consequence is interruption of that process.
Summary
What happened
Denial of service in Executable Books markdown-it-py before 2.2.0 allows local users to crash Markdown rendering with crafted input. The renderer assumes inline and image tokens always contain child-token lists and uses assertions instead of accepting an unset list; a malformed nested-image sequence violates that assumption and raises AssertionError. Exploitation requires attacker-controlled Markdown to reach an affected parser process, and the bounded consequence is interruption of that process.
The record
- CVE
- CVE-2023-26303
- Published
- Feb 22, 2023
- Updated
- Mar 11, 2025
- Vendor
- Executable Books
- Product
- markdown-it-py
- Classifications
- CWE-173, CAPEC-267, T1499.004
- Attack vector
- local
- Privileges
- authenticated
Timeline
How it unfolded
- Feb 22, 2023CVE publishedPublication date reported by the CVE source.
- Mar 11, 2025Record 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=0 <v2.2.0 changes=[{"at":"commit ae03c61","status":"unaffected"}]
What conditions does exploitation require?
What is affected?
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
No public exploit references are available in this record.
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