Vulnerability Report

CVE-2026-27166

Title: Discourse Codepen iframe URL manipulation

XSS

Proof Of Concept

No public PoC currently indexed for CVE-2026-27166.

CWE Category CWE-80
Published Date Mar 19, 2026
Modified Date Mar 25, 2026
Exploit Status Not Found
Score 4.1 CVSS v3.1
Exploit Probability (EPSS)
0.05%

Vulnerability Summary

CVE-2026-27166: Discourse is an open source discussion platform. Prior to versions 2026.3.0-latest.1, 2026.2.1 and 2026.1.2, insufficient cleanup in the default Codepen allowed iframes value allows an attacker to trick a user into changing the URL of the main page. This issue has been fixed in versions 2026.3.0-latest.1, 2026.2.1 and 2026.1.2. To workaround this issue, remove Codepen from the list of allowed iframes.

Impacted Vendors

D
discourse 1

Reference Links

https://github.com/discourse/discourse/commit/c4762a4fac2f61f52f325396b11d3aeb955ea925 https://github.com/discourse/discourse/security/advisories/GHSA-h653-cq78-vjj2
CVSS v3.1
Source Entity [email protected]
Severity MEDIUM
4.1
Attack Vector
NETWORK
Complexity
LOW
Privileges
N/A
Interaction
REQUIRED
Confidentiality
N/A
Integrity
N/A
Availability
N/A
Scope
CHANGED
RAW VECTOR CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:N/I:L/A:N
CVSS v3.1
Source Entity [email protected]
Severity MEDIUM
5.4
Attack Vector
NETWORK
Complexity
LOW
Privileges
N/A
Interaction
REQUIRED
Confidentiality
N/A
Integrity
N/A
Availability
N/A
Scope
CHANGED
RAW VECTOR CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N

Associated Attack Patterns (CAPEC)

Total: Patterns

CVE-2026-27166 Exploits & PoCs (Proof Of Concept)

No public PoCs found in our database for this CVE.

MODIFIED

Vulnerability data updated via NVD.

MODIFIED

Vulnerability data updated via NVD.

MODIFIED

Vulnerability data updated via NVD.

MODIFIED

Vulnerability data updated via NVD.

Attack Vector Matrix

Access Vector NETWORK
Complexity LOW
Privileges N/A
Interaction REQUIRED
CVSS Vector String CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:N/I:L/A:N

Affected Stack

No specific products linked.