CVE-2026-27934Network attack vector

Private topic metadata disclosure via missing visibility checks

Published Mar 19, 2026 · Updated Mar 19, 2026

Information disclosure in Discourse before 2026.3.0-latest.1, 2026.2.1, and 2026.1.2 allows remote attackers to read private topic metadata. The user action API builds activity results without applying topic visibility checks, returning a private topic's title and post excerpt to unauthorized requesters. No authentication or user interaction is required; disclosure is limited to the title and excerpt, with no reported write or service impact.

CVSS severity7.5
High
EPSS probability0.25%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Information disclosure in Discourse before 2026.3.0-latest.1, 2026.2.1, and 2026.1.2 allows remote attackers to read private topic metadata. The user action API builds activity results without applying topic visibility checks, returning a private topic's title and post excerpt to unauthorized requesters. No authentication or user interaction is required; disclosure is limited to the title and excerpt, with no reported write or service impact.

The record

CVE
CVE-2026-27934
Published
Mar 19, 2026
Updated
Mar 19, 2026
Vendor
Discourse
Product
Discourse
Classifications
CWE-201, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 19, 2026CVE publishedPublication date reported by the CVE source.
  2. Mar 19, 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=>= 2026.1.0-latest, < 2026.1.2
  2. Affected versionversion=>= 2026.2.0-latest, < 2026.2.1
  3. Affected versionversion== 2026.3.0-latest

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Discourse · Discourseversion=>= 2026.1.0-latest, < 2026.1.2; version=>= 2026.2.0-latest, < 2026.2.1; version== 2026.3.0-latest

Published CVSS scores

8.7GitHub, Inc.CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N
7.5National Institute of Standards and TechnologyCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/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
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-201Insertion of Sensitive Information Into Sent Data
T1190Exploit Public-Facing Application

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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