CVE-2026-44897
Description
Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.2.1, HTMLRenderer.heading() builds the opening <hN> tag by string-concatenating the id attribute value directly into the HTML — with no call to escape(), safe_entity(), or any other sanitisation function. A double-quote character " in the id value terminates the attribute, allowing an attacker to inject arbitrary additional attributes (event handlers, src=, href=, etc.) into the heading element. This vulnerability is fixed in 3.2.1.
Predictions
Heuristic predictions, AS-IS, for prioritization only.
Mitigations
No mitigations published for this CVE yet.
The vendor-content worker queues fetches as references arrive (check back in a few minutes). Or — if you've already worked around this in production — publish your fix to the community-verified tier.
✚ Propose a mitigation on Community → Mitigations published via the community go through AI scoring + 2 human reviewers + 7-day silent objection window before landing here withsource_tier=community-verified.
OS impact
Debian Affected 5 releases
| Version | Status | Fixed in |
|---|---|---|
| trixie | Affected | — |
| sid | Affected | — |
| forky | Affected | — |
| bullseye | Affected | — |
| bookworm | Affected | — |
SUSE Affected 1 release
| Version | Status | Fixed in |
|---|---|---|
| — | Affected | — |
Windows Affected 1 release
| Version | Status | Fixed in |
|---|---|---|
| — | Affected | — |
Application impact
| Vendor | Product | Versions | Fixed |
|---|---|---|---|
| mistune_project | mistune | {"endExcluding":"3.2.1"} | 3.2.1 |
References
- https://github.com/lepture/mistune/releases/tag/v3.2.1
- https://github.com/lepture/mistune/security/advisories/GHSA-v87v-83h2-53w7
- https://github.com/lepture/mistune
- https://www.suse.com/security/cve/CVE-2026-44897.html
- https://github.com/advisories/GHSA-v87v-83h2-53w7
- https://security-tracker.debian.org/tracker/CVE-2026-44897
- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-44897
CWEs
CWE-79
Community-verified mitigations for this CVE will appear above when contributors publish them.
Verify integrity in audit chain (admin only). AS-IS.