CVE-2021-43850Network attack vector

Admin-triggered service interruption via enabled diagnostics

Published Jan 4, 2022 · Updated Apr 22, 2025

Denial of service in Discourse before 2.7.12 and 2.8.0.beta through 2.8.0.beta9 allows remote authenticated users to interrupt service. The application initializer calls MessageBus.enable_diagnostics, unconditionally exposing a diagnostics route whose operations can exhaust server resources. An administrator must visit /message-bus/_diagnostics; on multisite deployments, an administrator of any hosted forum can interrupt the shared application server.

CVSS severity6.8
Medium
EPSS probability0.83%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Denial of service in Discourse before 2.7.12 and 2.8.0.beta through 2.8.0.beta9 allows remote authenticated users to interrupt service. The application initializer calls MessageBus.enable_diagnostics, unconditionally exposing a diagnostics route whose operations can exhaust server resources. An administrator must visit /message-bus/_diagnostics; on multisite deployments, an administrator of any hosted forum can interrupt the shared application server.

The record

CVE
CVE-2021-43850
Published
Jan 4, 2022
Updated
Apr 22, 2025
Vendor
Discourse
Product
Discourse
Classifications
CWE-20, T1499
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Jan 4, 2022CVE publishedPublication date reported by the CVE source.
  2. Apr 22, 2025Record 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=< 2.7.12
  2. Affected versionversion=>= 2.8.0.beta, < 2.8.0.beta10

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Discourse · Discourseversion=< 2.7.12; version=>= 2.8.0.beta, < 2.8.0.beta10

Published CVSS scores

8.2GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:H
6.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:N/I:N/A:H
4.0NIST NVDAV:N/AC:L/Au:S/C:N/I:N/A:P

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-20Improper Input Validation
T1499Endpoint Denial of Service

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

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo