CVE-2026-27154Network attack vector

Stored XSS via raw full-name HTML

Published Feb 26, 2026 · Updated Feb 26, 2026

Stored XSS in Discourse before 2025.12.2, 2026.1.1, and 2026.2.0 allows remote authenticated users to execute script via a crafted full name. The post editor evaluates the post author’s full name as raw HTML instead of escaping it for display. Exploitation requires display_name_on_posts enabled, prioritize_username_in_ux disabled, and a user with post-edit privileges to edit the malicious user’s post.

CVSS severity6.1
Medium
EPSS probability0.15%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

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Summary

What happened

Stored XSS in Discourse before 2025.12.2, 2026.1.1, and 2026.2.0 allows remote authenticated users to execute script via a crafted full name. The post editor evaluates the post author’s full name as raw HTML instead of escaping it for display. Exploitation requires display_name_on_posts enabled, prioritize_username_in_ux disabled, and a user with post-edit privileges to edit the malicious user’s post.

The record

CVE
CVE-2026-27154
Published
Feb 26, 2026
Updated
Feb 26, 2026
Vendor
Discourse
Product
Discourse
Classifications
CWE-79, T1203
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Feb 26, 2026CVE publishedPublication date reported by the CVE source.
  2. Feb 26, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 2025.12.2
  2. Affected versionversion=>= 2026.1.0-latest, < 2026.1.1
  3. Affected versionversion=>= 2026.2.0-latest, < 2026.2.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Discourse · Discourseversion=< 2025.12.2; version=>= 2026.1.0-latest, < 2026.1.1; version=>= 2026.2.0-latest, < 2026.2.0

Published CVSS scores

6.1NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
1.3GitHub, Inc.CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N/E:U

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1203Exploitation for Client Execution

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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