cvedb.io
CVE-2026-42857
MEDIUM · CVSS 4.6
EPSS exploitation probability: 0%
Published 2026-05-11T18:16:36.130 · Last modified 2026-06-17T10:48:31.077

Summary

Open edX Platform enables the authoring and delivery of online learning at any scale. The HTML sanitizer clean_thread_html_body() used for discussion notification emails fails to remove <style> tags from user-generated discussion post content. This content is rendered with Django's |safe template filter in email notification templates, allowing any enrolled student to inject arbitrary CSS into email notifications sent to other users. This enables email tracking (IP address disclosure), content spoofing, and phishing attacks. This vulnerability is fixed with commit cddc25cd791bb78f76833896e4778f668861df12.

Affected products

openedx — openedx

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References

This product uses data from the NVD API but is not endorsed or certified by the NVD. Informational only; not professional security advice.