🐹 Go

Not in CISA KEV

mo has a XSS via inline SVG script tags in Markdown renderingGHSA-vccx-p757-pv6h

GHSA-vccx-p757-pv6h is a security vulnerability in github.com/k1LoW/mo. A fix is available for github.com/k1LoW/mo — see the affected versions and patch details below.

Also known asGO-2026-4765

Published

Mar 18, 2026

Updated

Mar 23, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Mar 23, 2026 · OSV.dev, FIRST.org (EPSS)

Real-World Exposure

1 pkg affected

🐹github.com/k1LoW/mo

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.

Description

Summary

When rendering Markdown files containing inline SVG elements with <script> tags, the embedded JavaScript is executed in the browser. This is due to rehype-raw passing raw HTML (including SVG) through to the DOM without sanitization.

PoC

<svg><script>alert(1)</script></svg>

Embedding the above in a Markdown file opened with mo causes the script to execute.

Impact

Arbitrary JavaScript execution in the context of the mo application when a user opens a malicious Markdown file. This could lead to data exfiltration of other opened Markdown file contents.

Remediation

Fixed by adding rehype-sanitize to the Markdown rendering pipeline, which strips dangerous elements such as <script> while preserving safe HTML.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐹Go	`github.com/k1LoW/mo`	all versions	0.18.5`go get github.com/k1LoW/mo@v0.18.5`

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/k1LoW/mo, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update github.com/k1LoW/mo to 0.18.5 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-vccx-p757-pv6h is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Frequently Asked Questions

### Summary When rendering Markdown files containing inline SVG elements with `<script>` tags, the embedded JavaScript is executed in the browser. This is due to `rehype-raw` passing raw HTML (including SVG) through to the DOM without sanitization. ### PoC ```html <svg><script>alert(1)</script></svg> ``` Embedding the above in a Markdown file opened with mo causes the script to execute. ### Impact Arbitrary JavaScript execution in the context of the mo application when a user opens a malicious Markdown file. This could lead to data exfiltration of other opened Markdown file contents. ##

O3 Security · Impact-Aware SCA

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