CVE-2026-72724Network attack vector

Private chat disclosure via mismatched thread lookup

Published Aug 10, 2026 · Updated Aug 10, 2026

Authorization bypass in Discourse allows remote authenticated users to read private chat thread messages through onebox requests. The onebox handler resolves the user-supplied thread_id globally instead of within the route's channel_id, then checks preview access only for the selected channel. Any signed-in user who knows a private thread ID can pair it with a previewable public channel ID and receive that thread's message content; no write access or service interruption is reported.

CVSS severity4.3
Medium
EPSS probability0.46%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Authorization bypass in Discourse allows remote authenticated users to read private chat thread messages through onebox requests. The onebox handler resolves the user-supplied thread_id globally instead of within the route's channel_id, then checks preview access only for the selected channel. Any signed-in user who knows a private thread ID can pair it with a previewable public channel ID and receive that thread's message content; no write access or service interruption is reported.

The record

CVE
CVE-2026-72724
Published
Aug 10, 2026
Updated
Aug 10, 2026
Vendor
Discourse
Product
Discourse
Classifications
CWE-639, T1213.005
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Aug 10, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 10, 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=< 2026.1.6
  2. Affected versionversion=>= 2026.5.0-latest, < 2026.5.2
  3. Affected versionversion=>= 2026.6.0-latest, < 2026.6.1
  4. Affected versionversion=>= 2026.7.0-latest, < 2026.7.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Discourse · Discourseversion=< 2026.1.6; version=>= 2026.5.0-latest, < 2026.5.2; version=>= 2026.6.0-latest, < 2026.6.1; version=>= 2026.7.0-latest, < 2026.7.0

Published CVSS scores

4.3GitHub CNACVSS:3.1/AV:N/AC:L/PR:L/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 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-639Authorization Bypass Through User-Controlled Key
T1213.005Data from Information Repositories: Messaging 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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