CSS Injection Vulnerability in Open edX Platform by Open edX
CVE-2026-42857

4.6MEDIUM

Key Information:

Vendor

Openedx

Status
Openedx-platform
Vendor
CVE Published:
11 May 2026

What is CVE-2026-42857?

The Open edX Platform is susceptible to a CSS injection vulnerability due to the inadequate sanitization of user-generated content in discussion notification emails. The failure of the HTML sanitizer clean_thread_html_body() to remove tags permits attackers to inject arbitrary CSS into the email body. This functionality is leveraged through Django’s |safe template filter, which can lead to various security risks such as email tracking, IP address exposure, and potential phishing attacks on affected users. The issue has been rectified in the latest updates.

Affected Version(s)

openedx-platform < cddc25cd791bb78f76833896e4778f668861df12 < cddc25cd791bb78f76833896e4778f668861df12

openedx-platform >= sumac, < ulmo < sumac, ulmo

References

https://github.com/openedx/openedx-platform/security/advi...
x_refsource_CONFIRM
https://github.com/openedx/openedx-platform/commit/cddc25...
x_refsource_MISC

CVSS V3.1

Score:
4.6
Severity:
MEDIUM
Confidentiality:
Low
Integrity:
Low
Availability:
Low
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
Low
User Interaction:
Required
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

.