CVE-2026-42857
Medium · 4.6CVSS
4.6
EPSS
0.3%
Published
May 11, 2026
CISA due date
—
The record
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 packages
| Ecosystem | Package | Introduced | Fixed |
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Related vulnerabilities
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- CVE-2026-96362 Improper Neutralization of Input During Web Page Generation ("Cross-site Scripting")… CWE-79
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- CVE-2026-96357 Improper Neutralization of Input During Web Page Generation ("Cross-site Scripting")… CWE-79
- CVE-2026-96358 Improper Neutralization of Input During Web Page Generation ("Cross-site Scripting")… CWE-79