CVE-2026-42857

4.6 MEDIUM
Published: May 11, 2026 Modified: May 13, 2026
View on NVD

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.

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CVSS v3.x Details

0.0 Low Medium High Critical 10.0
Vector String
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:L/A:N

References to Advisories, Solutions, and Tools

Patch Vendor Advisory Exploit Third Party Advisory

3 reference(s) from NVD

Quick Stats

CVSS v3 Score
4.6 / 10.0
EPSS (Exploit Probability)
0.2%
11th percentile
Exploitation Status
Not in CISA KEV

Weaknesses (CWE)

Affected Vendors

openedx