VULNERABILITY INTELLIGENCE

CVE-2026-42857

CVSS score4.6 MEDIUM
EPSS probability0.18%
CISA KEVNot currently listed
Published2026-05-11
Last modified2026-10-26
CVSS vectorCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:L/A:N

Description

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.

Weakness classification

  • security-advisories@github.com: CWE-79

Primary references