Description
Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.2.1, render_admonition() in src/mistune/directives/admonition.py concatenates the Admonition directive :class: option into the HTML class attribute without escaping, allowing attribute injection and cross-site scripting even when HTMLRenderer escape mode is enabled. This issue is fixed in version 3.2.1.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| lepture | mistune | < 3.2.1 | — |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | mistune | 3.1.4-1 | — |
| Debian 13 | mistune | No fix yet | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.10 | mistune | No fix yet | — |
| Ubuntu 26.04 LTS | mistune | No fix yet | — |
| Ubuntu 25.10 | mistune | No fix yet | — |
| Ubuntu 24.04 LTS | mistune | No fix yet | — |
| Ubuntu 22.04 LTS | mistune | No fix yet | — |
Show 3 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 20.04 LTS | mistune | No fix yet | — |
| Ubuntu 18.04 LTS | mistune | No fix yet | — |
| Ubuntu 16.04 LTS | mistune | No fix yet | — |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES for SAP 16.0 | python-mistune | 3.1.3-160000.5.1 | SUSE-SU-2026:22655-1 |
| SLES 16.0 | python-mistune | 3.1.3-160000.5.1 | SUSE-SU-2026:22655-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Leap 16.0 | python-mistune | 3.1.3-160000.5.1 | openSUSE-SU-2026:21339-1 |
Azure Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Azure Linux 3 | python-mistune | 3.3.0-1 | — |
Affected packages
| Ecosystem | Package | Affected | Fixed | Record |
|---|---|---|---|---|
| PyPI | mistune | < 3.3.0 | 3.3.0 | GHSA-g97x-gvcm-x72h |
Advisories 2
- SUSE-SU-2026:22655-1 Security update for python-mistune SUSE / openSUSE Security Updates · Jul 17, 2026
- openSUSE-SU-2026:21339-1 Security update for python-mistune SUSE / openSUSE Security Updates · Jul 15, 2026