CVE-2026-42857

MEDIUM EPSS 11.3%
Published May 11, 20261mo ago · Modified Jun 17, 20262w ago
5.4 CVSS 3.1
Medium
Find Similar
Published May 11, 2026 1mo ago
Last Modified Jun 17, 2026 2w ago

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.

CVSS Details

Base Score
5.4
Exploitability
2.3
Impact
2.7
Vector string
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
Attack Vector Network
Attack Complexity Low
Privileges Required Low
User Interaction Required
Scope Changed
Confidentiality Low
Integrity Low
Availability None

Threat Intelligence

EPSS Exploit Probability
11.3% percentile
Exploit & Patch Status
Public Exploit Known
Patch Available

Weaknesses 1

CWE-79 Cross-site Scripting Injection

Affected Products 1

VendorProductVersionRange
openedxopenedx* <2026-04-24

References 2

  • github.com https://github.com/openedx/openedx-platform/commit/cddc25cd791bb78f76833896e4778f668861df12
    Patch
  • github.com https://github.com/openedx/openedx-platform/security/advisories/GHSA-4xv3-5j4x-q8g4
    ExploitVendor Advisory

Remediation

  • github.com https://github.com/openedx/openedx-platform/commit/cddc25cd791bb78f76833896e4778f668861df12
    Patch