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CVE-2026-42857

23
FAUCET Score

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.

First published: May 11, 2026Last modified: May 11, 2026

Impacted Technologies

VendorProductVersion(s)CPE
< 2026-04-24CPE matchmatch criteria
cpe:2.3:a:openedx:openedx:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

4.6MEDIUM

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:L/A:N

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality Impact
LOW
Integrity Impact
LOW
Availability Impact
NONE
Exploitability Score
2.1
Impact Score
2.5
CvssVersion
3.1

Exploit Intelligence

EPSS Score
0.21%
Probability of exploitation in next 30 days
EPSS Percentile
11.4%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0021 is in the 13th percentile among its peer group of 15,225 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.0 Bluesky, 0.0 Mastodon, and 0.1 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.0 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Remediation records are not available for this CVE.

References

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