PT-2026-39712 · Open Edx · Open Edx Platform

Published 2026-05-11 · Updated 2026-05-11 · CVE-2026-42857

Mitre

CVSS v3.1

4.6

Medium

Base vector

AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:L/A:N

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.

Fix

XSS

Weakness Enumeration

CWE-79

Related Identifiers

CVE-2026-42857

Affected Products

Open Edx Platform

References · 3

• https://nvd.nist.gov/vuln/detail/CVE-2026-42857 · Security Note
• https://github.com/openedx/openedx-platform/security/advisories/GHSA-4xv3-5j4x-q8g4 · Note
• https://github.com/openedx/openedx-platform/commit/cddc25cd791bb78f76833896e4778f668861df12 · Note