CVE-2026-27166
Discourse vulnerable to HTML injection via prohibited iframe URLs
Description
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.
INFO
Published Date :
March 19, 2026, 9:17 p.m.
Last Modified :
March 19, 2026, 9:17 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
Affected Products
The following products are affected by CVE-2026-27166
vulnerability.
Even if cvefeed.io is aware of the exact versions of the
products
that
are
affected, the information is not represented in the table below.
No affected product recoded yet
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 3.1 | MEDIUM | [email protected] |
Solution
- Update Discourse to version 2026.3.0-latest.1.
- Update Discourse to version 2026.2.1.
- Update Discourse to version 2026.1.2.
- Remove Codepen from allowed iframes.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-27166.
| URL | Resource |
|---|---|
| https://github.com/discourse/discourse/commit/c4762a4fac2f61f52f325396b11d3aeb955ea925 | |
| https://github.com/discourse/discourse/security/advisories/GHSA-h653-cq78-vjj2 |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-27166 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-27166
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-27166 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-27166 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
New CVE Received by [email protected]
Mar. 19, 2026
Action Type Old Value New Value Added Description 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. Added CVSS V3.1 AV:N/AC:L/PR:L/UI:R/S:C/C:N/I:L/A:N Added CWE CWE-80 Added Reference https://github.com/discourse/discourse/commit/c4762a4fac2f61f52f325396b11d3aeb955ea925 Added Reference https://github.com/discourse/discourse/security/advisories/GHSA-h653-cq78-vjj2