What’s Vulnerable › Vulnerabilities

CVE-2023-26303: markdown-it-py crash on null assertions

• Severity: medium (CVSS 5.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.2% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2023-02-23 · updated 2026-06-17
• Weakness: CWE-173

Description

Denial of service could be caused to markdown-it-py, before v2.2.0, if an attacker was allowed to force null assertions with specially crafted input.

Affected products

• Executable Books markdown-it-py: before 2.2.0 — fixed in 2.2.0

How to fix

Upgrade to a fixed version: Executable Books markdown-it-py 2.2.0. Check the vendor advisory for mitigations.

References

• https://github.com/executablebooks/markdown-it-py/commit/ae03c6107dfa18e648f6fdd1280f5b89092d5d49
• https://github.com/executablebooks/markdown-it-py/commit/ae03c6107dfa18e648f6fdd1280f5b89092d5d49

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