CVE-2026-27152Network attack vector

Authenticated DM access-control bypass via unchecked member addition

Published Feb 26, 2026 · Updated Feb 26, 2026

Access-control bypass in Discourse before 2025.12.2, 2026.1.1, and 2026.2.0 allows remote authenticated users to add blocked users to DMs. Chat::AddUsersToChannel adds members to an existing direct-message channel without applying the per-recipient block, ignore, mute, and private-message checks used during channel creation. An authenticated user must control an existing direct-message channel; the consequence is forced membership despite the target's communication preferences.

CVSS severity3.5
Low
EPSS probability0.16%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Access-control bypass in Discourse before 2025.12.2, 2026.1.1, and 2026.2.0 allows remote authenticated users to add blocked users to DMs. Chat::AddUsersToChannel adds members to an existing direct-message channel without applying the per-recipient block, ignore, mute, and private-message checks used during channel creation. An authenticated user must control an existing direct-message channel; the consequence is forced membership despite the target's communication preferences.

The record

CVE
CVE-2026-27152
Published
Feb 26, 2026
Updated
Feb 26, 2026
Vendor
Discourse
Product
Discourse
Classifications
CWE-284
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

1.3GitHub, Inc.CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:U
3.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:L/I:L/A:N

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-284Improper Access Control

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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