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Vulnerabilities

Vulnerability · CVE-2026-44898

Mistune is a Python Markdown parser with renderers and plugins.

Published May 26, 2026 · catalog updated Jul 24, 2026 · mistune project

Check if you run it

No confirmed exploitation is on record for CVE-2026-44898. EPSS is 0.27%. Act only if a listed version of mistune project is installed.

Gaps on this record

  • No version range is stored. A customer cannot check an installed version against this record.
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
Medium6.1
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.27%
Remediation
Advisory link
Affected products
cpe mistune project/mistune

Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.2.1, render_toc_ul() builds a table-of-contents tree from a list of (level, id, text) tuples. Both the id value (used as href="# ") and the text value (used as the visible link label) are inserted into tags via a plain Python format string — with no HTML escaping applied to either value. When heading IDs are derived from user-supplied heading text (the standard use-case for readable slug anchors), an attacker can craft a heading whose text breaks out of the href="#..." attribute context, injecting arbitrary HTML tags including blocks directly into the rendered TOC. This vulnerability is fixed in 3.2.1.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • cpe mistune project/mistuneversion unspecified

How to fix CVE-2026-44898

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-44898. EPSS is 0.27%. Act only if a listed version of mistune project is installed.

Which versions are affected?

Affected version ranges are not on this record. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-79: Cross-site Scripting (XSS). EPSS 0.27%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. May 26, 2026 · NIST NVD

    Detected

    Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.2.1, render_toc_ul() builds a table-of-contents tree from a list of (level, id, text) tuples. Both the id value (used as href="# ") and the text value (used as the visible link label) are inserted into tags via a plain Python format string — with no HTML escaping applied to either value. When heading IDs are derived from us

  2. Jul 24, 2026 · NIST NVD

    Updated

    Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.2.1, render_toc_ul() builds a table-of-contents tree from a list of (level, id, text) tuples. Both the id value (used as href="# ") and the text value (used as the visible link label) are inserted into tags via a plain Python format string — with no HTML escaping applied to either value. When heading IDs are derived from us

Sources

  • CVE.orgVulnerability recordCVE-2026-44898

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-44898

    30-day exploitation probability 0.3%

    first.org
  • NIST NVDVulnerability recordCVE-2026-44898

    Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.2.1, render_toc_ul() builds a table-of-contents tree from a list of (level, id, text) tuples. Both the id value (used as href="# ") and the text value (used as the visible link label) are inserted

    nvd.nist.gov

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.