# CVE-2026-44708: Mistune Math Plugin XSS Escape Bypass

> An XSS vulnerability in the Mistune math plugin allows attackers to inject malicious scripts via unescaped math content, even when escaping is enabled.

- **Severity:** Medium 6.1 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 26 May 2026
- **Updated:** 27 May 2026
- **Also known as:** AZL-88397, DEBIAN-CVE-2026-44708, GHSA-8g87-j6q8-g93x, PYSEC-2026-2206, UBUNTU-CVE-2026-44708

## What is CVE-2026-44708?

CVE-2026-44708 is a medium-severity cross-site scripting vulnerability in lepture mistune, published on 26 May 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official description

Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.2.1, the mistune math plugin renders inline math ($...$) and block math ($$...$$) by concatenating the raw user-supplied content directly into the HTML output without any HTML escaping. This occurs even when the parser is explicitly created with escape=True, which is supposed to guarantee that all user-controlled text is sanitised before reaching the DOM. This vulnerability is fixed in 3.2.1.

Weakness: CWE-79 (Improper Neutralization of Input During Web Page Generation)

## Which versions are affected by CVE-2026-44708?

3 open source packages ship an affected version, including mistune. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `mistune` | PyPI | All versions to 3.2.0 | None |
| `mistune` | PyPI | All versions to 3.2.0 | None |
| `mistune` | PyPI | All versions | 3.2.1 |

Products: Mistune Project Mistune.

## How do I fix CVE-2026-44708?

Upgrade mistune to 3.2.1 or later.

## Is CVE-2026-44708 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-44708 exists.

## Other vulnerabilities in lepture mistune

- [CVE-2026-59922](https://insights.sbomify.com/CVE-2026-59922/): Mistune plugins/formatting: quadratic-time parsing on long runs of `~~x~~`, `==x==`, and `^^x^^` markers (strikethrough / mark / insert) (high 7.5)
- [CVE-2026-59925](https://insights.sbomify.com/CVE-2026-59925/): inline_parser: quadratic-time parsing on long runs of `**x**` and `***x***` emphasis pairs (high 7.5)
- [CVE-2026-59928](https://insights.sbomify.com/CVE-2026-59928/): Mistune block_parser: quadratic-time parsing on long lists of repeated reference-link definitions (high 7.5)
- [CVE-2026-59923](https://insights.sbomify.com/CVE-2026-59923/): Mistune: XSS via percent-encoded javascript URI bypass in safe_url() (medium 6.1)
- [CVE-2026-59929](https://insights.sbomify.com/CVE-2026-59929/): Mistune renderers/html.safe_url: HARMFUL_PROTOCOLS list misses legacy and chained schemes that historically chain to `javascript:` execution (medium 6.1)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-44708 and fix it if it is affected.

What it is: CVE-2026-44708 is a medium-severity cross-site scripting vulnerability in lepture mistune, published on 26 May 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-44708 exists.

Affected packages and fixed versions:
- mistune (PyPI): affected all versions up to 3.2.0; no fix listed
- mistune (PyPI): affected all versions up to 3.2.0; no fix listed
- mistune (PyPI): affected all versions; fixed in 3.2.1

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-44708/ (Markdown: https://insights.sbomify.com/CVE-2026-44708/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-44708
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-44708
- OSV: https://osv.dev/vulnerability/CVE-2026-44708

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-44708/
Summaries are generated and may contain mistakes; the official description above is the record.