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Findings

CVE-2026-42857

Open edX Platform enables the authoring and delivery of online learning at any scale.

Published May 11, 2026 · updated Jun 17, 2026 · openedx openedx

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 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.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. May 11, 2026 · NIST NVD

    Detected

    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 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 notif

  2. Jun 17, 2026 · NIST NVD

    Updated

    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 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 notif

Affected

  • cpe openedx/openedxversion unspecified

Sources

  • CVE.orgVulnerability recordCVE-2026-42857

    Official CVE identifier

    cve.org
  • NIST NVDVulnerability recordCVE-2026-42857

    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 tags from user-generated discussion post content. This content is rendered with Django

    nvd.nist.gov

References