Summary
mo has a XSS via inline SVG script tags in Markdown rendering
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.
Untrusted input is rendered as active markup in a victim's browser, which can run script in their session. Typical impact: session or credential theft, and actions taken as the user.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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Fixed by adding rehype-sanitize to the Markdown rendering pipeline, which strips dangerous elements such as <script> while preserving safe HTML.
Frequently Asked Questions
- What is GHSA-VCCX-P757-PV6H? GHSA-VCCX-P757-PV6H is a low-severity cross-site scripting (XSS) vulnerability in github.com/k1LoW/mo (go), affecting versions <= 0.18.4. It is fixed in 0.18.5. Untrusted input is rendered as active markup in a victim's browser, which can run script in their session.
- Which versions of github.com/k1LoW/mo are affected by GHSA-VCCX-P757-PV6H? github.com/k1LoW/mo (go) versions <= 0.18.4 is affected.
- Is there a fix for GHSA-VCCX-P757-PV6H? Yes. GHSA-VCCX-P757-PV6H is fixed in 0.18.5. Upgrade to this version or later.
- Is GHSA-VCCX-P757-PV6H exploitable, and should I be worried? Whether GHSA-VCCX-P757-PV6H is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether GHSA-VCCX-P757-PV6H is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix GHSA-VCCX-P757-PV6H? Upgrade
github.com/k1LoW/moto 0.18.5 or later.