Discourse up to 2025.12.1/2026.1.0 cross site scripting

CVSS Meta Temp Score
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CTI Interest Score
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4.7$0-$5k0.00

Summaryinfo

A vulnerability labeled as problematic has been found in Discourse up to 2025.12.1/2026.1.0. The affected element is an unknown function. Such manipulation leads to cross site scripting. This vulnerability is traded as CVE-2026-27154. The attack may be launched remotely. There is no exploit available. The affected component should be upgraded.

Detailsinfo

A vulnerability was found in Discourse up to 2025.12.1/2026.1.0 and classified as problematic. Affected by this issue is an unknown part. The manipulation with an unknown input leads to a cross site scripting vulnerability. Using CWE to declare the problem leads to CWE-79. The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users. Impacted is integrity. CVE summarizes:

Discourse is an open source discussion platform. Prior to versions 2025.12.2, 2026.1.1, and 2026.2.0, a user full name can be evaluated as raw HTML when the following settings are set: `display_name_on_posts` => true; and `prioritize_username_in_ux` => false. Editing a post of a malicious user would trigger an XSS. Versions 2025.12.2, 2026.1.1, and 2026.2.0 patch the issue. No known workarounds are available.

The advisory is available at github.com. This vulnerability is handled as CVE-2026-27154 since 02/18/2026. The exploitation is known to be easy. The attack may be launched remotely. Successful exploitation requires user interaction by the victim. The technical details are unknown and an exploit is not available. This vulnerability is assigned to T1059.007 by the MITRE ATT&CK project.

Upgrading to version 2025.12.2, 2026.1.1 or 2026.2.0 eliminates this vulnerability.

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Productinfo

Type

Name

Version

License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA CVSS-B Score: 🔒
CNA CVSS-BT Score: 🔒
CNA Vector: 🔒

CVSSv3info

VulDB Meta Base Score: 4.8
VulDB Meta Temp Score: 4.7

VulDB Base Score: 3.5
VulDB Temp Score: 3.4
VulDB Vector: 🔒
VulDB Reliability: 🔍

NVD Base Score: 6.1
NVD Vector: 🔒

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Cross site scripting
CWE: CWE-79 / CWE-94 / CWE-74
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Discourse 2025.12.2/2026.1.1/2026.2.0

Timelineinfo

02/18/2026 CVE reserved
02/27/2026 +9 days Advisory disclosed
02/27/2026 +0 days VulDB entry created
03/03/2026 +4 days VulDB entry last update

Sourcesinfo

Product: github.com

Advisory: GHSA-xv43-5gcp-wgw8
Status: Confirmed

CVE: CVE-2026-27154 (🔒)
GCVE (CVE): GCVE-0-2026-27154
GCVE (VulDB): GCVE-100-348134

Entryinfo

Created: 02/27/2026 08:04
Updated: 03/03/2026 12:17
Changes: 02/27/2026 08:04 (68), 03/03/2026 12:17 (13)
Complete: 🔍
Cache ID: 216::103

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