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Advisory severityHigh7.5Red Hat Linux

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 Red Hat OpenShift AI (RHOAI), Red Hat OpenShift Container Platform 4.

Aggregated and source-linked by VulniPulse. Data sources, validation and limitations.

CVE-2026-76098 Source published Source updated

VulniPulse record published Record updated

CVE-2026-76098
Affected products & platforms
Red Hat LinuxUnclassified
Open source advisory

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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: Red Hat OpenShift AI (RHOAI); Red Hat OpenShift Container Platform 4. Red Hat lists Migration Toolkit for Applications 8; Red Hat OpenShift AI (RHOAI) as not affected.

Red Hat does not currently list a fixing RHSA for this CVE.

Affected versions
  • 3.3.0
  • 3.3.2

Official advisory · high-confidence parse· fetched 13 days ago·verify at source

Fixed versions
  • 3.3.3

Official advisory · high-confidence parse· fetched 13 days ago·verify at source

Mitigation checklist

Recommended fix / mitigation
  • Mitigation for this issue involves restricting the processing of untrusted Markdown content by applications utilizing the vulnerable Mistune library. If applications are exposed to untrusted input, implement input sanitization to prevent deeply nested emphasis structures that could trigger the denial of service.

Official advisory · high-confidence parse· fetched 13 days ago·verify at source

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