CVE-2026-42857
MEDIUM
MEDIUM
Priority: 0.01
BB Relevance:
51/100
Published: 2026-05-11
Modified: 2026-10-26
First seen: 2026-10-29
Status: active
Attack Surface
Network
Low Complexity
Scope Change
CVSS Vector Breakdown
AV:
Network
AC:
Low
PR:
Low
UI:
Required
S:
Changed
C:
Low
I:
Low
A:
None
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 (1)
References & Advisories (2)
Patch
Exploit
Vendor Advisory