CVE-2026-27166

Name: CVE-2026-27166
Creator: NVD / NIST
Published: 2026-03-19T21:17:08.74+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 5.4/10EPSS 0.19%

Last modified Jun 17, 2026

CVE-2026-27166 is a medium-severity vulnerability rated 5.4/10 on the CVSS scale. 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. EPSS estimates a 0.19% chance of exploitation in the next 30 days.

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.

Metrics

CVSS 3.1

5.4/10

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

EPSS Probability

0.19%

8.5th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-80

Affected Software

Vendor	Product	Versions
Discourse	Discourse	< 2026.3.0
Discourse	Discourse	>= 2026.1.0, < 2026.1.2
Discourse	Discourse	>= 2026.2.0, < 2026.2.1
Discourse	Discourse	2026.3.0

References

Timeline

Published: Mar 19, 2026
Last Modified: Jun 17, 2026
Status: Analyzed

Frequently Asked Questions

What is CVE-2026-27166?

How severe is CVE-2026-27166?

CVE-2026-27166 has a CVSS score of 5.4/10 (MEDIUM severity). The EPSS model estimates a 0.19% probability of exploitation in the next 30 days.

How do I fix CVE-2026-27166?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2026-27166?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST