Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.2.1, render_toc_ul() builds a <ul> table-of-contents tree from a list of (level, id, text) tuples. Both the id value (used as href="#<id>") and the text value (used as the visible link label) are inserted into <a> 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 <script> blocks directly into the rendered TOC. This vulnerability is fixed in 3.2.1.

The remote Fedora 45 host has a package installed that is affected by a vulnerability as referenced in the FEDORA-2026-182b5d52c9 advisory.

    Automatic update for python-mistune-3.2.1-1.fc45.

    ##### **Changelog**

    ```
    * Thu Jun 18 2026 Miro Hronok <miro@hroncok.cz> - 3.2.1-1
    - Update to 3.2.1
    - Security fix for CVE-2026-44898
    - Fixes: rhbz#2424578
    - Fixes: rhbz#2489782

    ```

Tenable has extracted the preceding description block directly from the Fedora security advisory.

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

The remote SUSE Linux SLES16 / SLES_SAP16 host has a package installed that is affected by multiple vulnerabilities as referenced in the SUSE-SU-2026:21858-1 advisory.

    This update for python-mistune fixes the following issues

    - CVE-2026-33079: ReDoS in `LINK_TITLE_RE` can lead to denial of service via a crafted Markdown     (bsc#1264347).
    - CVE-2026-33441: processing of malformed reference links can lead to excessive resource consumption and     denial of       service (bsc#1264752).
    - CVE-2026-44708: improper HTML escaping in the math plugin can lead to XSS (bsc#1264751).
    - CVE-2026-44896: improper escaping in `render_figure` can lead to attribute injection and XSS     (bsc#1264754).
    - CVE-2026-44897: improper sanitization of user-controlled input in `HTMLRenderer.heading` can lead to XSS       (bsc#1264750).
    - CVE-2026-44898: improper sanitization of user-supplied HTML input in `render_toc_ul` can lead to XSS     (bsc#1265052).
    - CVE-2026-44899: improper input verification in Image directive plugin and improper escaping in     `render_block_image`       can lead to CSS injection (bsc#1265053).

Tenable has extracted the preceding description block directly from the SUSE security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The remote openSUSE 16 host has a package installed that is affected by multiple vulnerabilities as referenced in the openSUSE-SU-2026:20827-1 advisory.

    This update for python-mistune fixes the following issues

    - CVE-2026-33079: ReDoS in `LINK_TITLE_RE` can lead to denial of service via a crafted Markdown     (bsc#1264347).
    - CVE-2026-33441: processing of malformed reference links can lead to excessive resource consumption and     denial of       service (bsc#1264752).
    - CVE-2026-44708: improper HTML escaping in the math plugin can lead to XSS (bsc#1264751).
    - CVE-2026-44896: improper escaping in `render_figure` can lead to attribute injection and XSS     (bsc#1264754).
    - CVE-2026-44897: improper sanitization of user-controlled input in `HTMLRenderer.heading` can lead to XSS       (bsc#1264750).
    - CVE-2026-44898: improper sanitization of user-supplied HTML input in `render_toc_ul` can lead to XSS     (bsc#1265052).
    - CVE-2026-44899: improper input verification in Image directive plugin and improper escaping in     `render_block_image`       can lead to CSS injection (bsc#1265053).

Tenable has extracted the preceding description block directly from the SUSE security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available.

  - Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.2.1, render_toc_ul() builds a     <ul> table-of-contents tree from a list of (level, id, text) tuples. Both the id value (used as     href=#<id>) and the text value (used as the visible link label) are inserted into <a> 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 <script> blocks directly into the rendered TOC. This vulnerability is fixed in 3.2.1.
    (CVE-2026-44898)

Note that Nessus relies on the presence of the package as reported by the vendor.

ID	Name	Product	Family	Severity
321736	Fedora 45 : python-mistune (2026-182b5d52c9)	Nessus	Fedora Local Security Checks	medium
318185	SUSE SLES16 Security Update : python-mistune (SUSE-SU-2026:21858-1)	Nessus	SuSE Local Security Checks	high
318089	openSUSE 16 Security Update : python-mistune (openSUSE-SU-2026:20827-1)	Nessus	SuSE Local Security Checks	high
317360	Linux Distros Unpatched Vulnerability : CVE-2026-44898	Nessus	Misc.	medium

Detections

Analytics

CVE-2026-44898

medium

Tenable Plugins

medium

high

high

medium