CVE catalog

CVE-2026-44899

Mistune is a Python Markdown parser with renderers and…

[CVE catalog]

Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.2.1, the Image directive plugin validates the :width: and :height: options with a regex compiled as _num_re = re.compile(r"^\d+(?:\.\d*)?"). When the validated value is not a plain integer, render_block_image() inserts it directly into a style="width:...;" or style="height:...;" attribute. Because the value was accepted by the prefix-only regex, any CSS after the leading digits reaches the style= attribute verbatim and without escaping. This vulnerability is fixed in 3.2.1.

Severity
Medium · CVSS 6.1CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Published
Source
[NVD] · [CVE record]
EPSS
0.23% · Oct 27, 2026

Projects and upstream resources

Reported versions and fixes

Each observation applies to its named package, distribution, and release. Distribution backports can fix a vulnerability while retaining an older upstream version number.

Version impact has not been established. The original provider fields are retained below.

Provider details and historical evidence
Original provider fields
{
  "package_releases": [
    {
      "name": "mistune",
      "status": "fixed",
      "release": "sid",
      "version": "3.4.0-1"
    },
    {
      "name": "mistune",
      "status": "vulnerable",
      "release": "forky",
      "version": "3.1.4-1"
    },
    {
      "name": "mistune",
      "status": "vulnerable",
      "release": "trixie",
      "version": "3.1.3-1"
    },
    {
      "name": "mistune",
      "status": "vulnerable",
      "release": "bookworm",
      "version": "2.0.4-1"
    }
  ],
  "fixed_versions": [
    {
      "bug": 1138260,
      "name": "mistune",
      "type": "source",
      "origin": null,
      "release": "sid",
      "urgency": "not yet assigned",
      "fixed_version": "3.3.4-1"
    },
    {
      "bug": 1138260,
      "name": "mistune",
      "type": "source",
      "origin": null,
      "release": "forky",
      "urgency": "not yet assigned",
      "fixed_version": ""
    },
    {
      "bug": 1138260,
      "name": "mistune",
      "type": "source",
      "origin": null,
      "release": "trixie",
      "urgency": "not yet assigned",
      "fixed_version": ""
    },
    {
      "bug": 1138260,
      "name": "mistune",
      "type": "source",
      "origin": null,
      "release": "bookworm",
      "urgency": "not yet assigned",
      "fixed_version": ""
    }
  ],
  "distribution_packages": [
    {
      "name": "mistune",
      "ecosystem": "cpe",
      "fixed_version": "not yet fixed"
    },
    {
      "name": "mistune",
      "ecosystem": "cpe",
      "fixed_version": "3.2.1"
    },
    {
      "name": "mistune",
      "ranges": [
        {
          "type": "ECOSYSTEM",
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "3.2.1"
            }
          ]
        }
      ],
      "ecosystem": "PyPI",
      "fixed_version": "3.2.1"
    }
  ]
}

[Debian bug #1138260]

Publisher notes

[trixie] mistune: Minor issue [bookworm] mistune: Minor issue

OpenFactory catalog packages

Matching against OpenFactory catalog package versions is in progress.

[Debian 12 (Bookworm)]

  • [python3-mistune]Unknown

    Source package: [mistune]

    Details (2)

    • 2.0.4-1 · all · bookworm

      Affected

      nvd · mistune · debian · bookworm; nvd · mistune · debian · 12

    • 2.0.4-1 · all · bookworm

      Affected

      nvd · mistune · debian · bookworm; nvd · mistune · debian · 12

[Debian 13 (Trixie)]

  • [python3-mistune]Unknown

    Source package: [mistune]

    Details (2)

    • 3.1.3-1 · all · trixie

      Affected

      nvd · mistune · debian · 13

    • 3.1.3-1 · all · trixie

      Affected

      nvd · mistune · debian · 13

Observed:

References

[Debian Security Tracker] · [FIRST EPSS] · [National Vulnerability Database (NVD)] · [OSV Package Vulnerability Database] · [Red Hat security advisories and VEX] · [SUSE security advisories and VEX]