High [CVE-2026-76098] Denial of Service via excessive emphasis markers in Markdown
This high-severity Red Hat Linux advisory covers CVE-2026-76098 affecting Migration Toolkit for Applications 8, Red Hat OpenShift AI (RHOAI), Red Hat OpenShift Container Platform 4.
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Summary
Mistune is a Python Markdown parser with renderers and plugins. Versions 3.3.0 through 3.3.2 are vulnerable to DoS through deeply nested tokens.
HTML rendering creates deeply nested emphasis tokens from consecutive asterisk characters, and recursive rendering in HTMLRenderer.render_token() can exceed Python's recursion limit and raise RecursionError, allowing crafted Markdown to crash a parsing process.
This issue is fixed in version 3.3.3 This vulnerability allows a remote attacker to trigger a Denial of Service (DoS) by submitting specially crafted Markdown input. The excessive use of emphasis markers, such as consecutive asterisks, creates deeply nested tokens during HTML rendering.
Red Hat severity: Important — CVSS 7.5 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H). Weakness: CWE-770.
Affected Red Hat products: Migration Toolkit for Applications 8; Red Hat OpenShift AI (RHOAI); Red Hat OpenShift Container Platform 4. Red Hat does not currently list a fixing RHSA for this CVE.
- 3.3.0
- 3.3.2
Official advisory · high-confidence parse· fetched 36 minutes ago·verify at source
- 3.3.3
Official advisory · high-confidence parse· fetched 36 minutes ago·verify at source
Mitigation
Upgrade to a fixed release: 3.3.3. That is the remediation for this advisory.
The vendor advisory may list additional interim mitigations or workarounds not captured here — review it before change work.
Official advisory · high-confidence parse· fetched 36 minutes ago·verify at source
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