CVE-2026-45085Network attack vector

Message disclosure and thread manipulation via missing authorization

Published Jun 12, 2026 · Updated Jun 12, 2026

Authorization flaws in Discourse chat allow remote attackers to disclose private messages or perform unauthorized thread actions. The chat plugin omits authorization checks when creating or restoring chat content and serializes last_message into flag-review and calendar payloads without verifying channel access. Chat must be enabled; the calendar exposure also requires discourse-calendar, while other paths require read-only membership, message authorship, or moderator review.

CVSS severity5.3
Medium
EPSS probability0.21%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Authorization flaws in Discourse chat allow remote attackers to disclose private messages or perform unauthorized thread actions. The chat plugin omits authorization checks when creating or restoring chat content and serializes last_message into flag-review and calendar payloads without verifying channel access. Chat must be enabled; the calendar exposure also requires discourse-calendar, while other paths require read-only membership, message authorship, or moderator review.

The record

CVE
CVE-2026-45085
Published
Jun 12, 2026
Updated
Jun 12, 2026
Vendor
Discourse
Product
Discourse
Classifications
CWE-200, CWE-862, T1213.005
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 12, 2026CVE publishedPublication date reported by the CVE source.
  2. Jun 12, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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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, < 2026.1.4
  2. Affected versionversion=>= 2026.3.0-latest, < 2026.3.1
  3. Affected versionversion=>= 2026.4.0-latest, < 2026.4.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Discourse · Discourseversion=>= 2026.1.0-latest, < 2026.1.4; version=>= 2026.3.0-latest, < 2026.3.1; version=>= 2026.4.0-latest, < 2026.4.1

Published CVSS scores

5.3GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-200Exposure of Sensitive Information to an Unauthorized Actor
CWE-862Missing Authorization
T1213.005Messaging Applications

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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