CVE-2025-32376Network attack vector

DM participant-limit bypass via incomplete membership count

Published Apr 30, 2025 · Updated Apr 30, 2025

Improper access control in Discourse before 3.4.3 and 3.5.0.beta1 through 3.5.0.beta2 allows remote authenticated users to overfill DMs. Chat::AddUsersToChannel excluded existing channel participants before evaluating the maximum-user policy, so repeated additions were checked only against newly supplied users. A user who has joined a direct-message channel can add participants beyond the configured limit, potentially placing every site user in one conversation and consuming service resources.

CVSS severity4.8
Medium
EPSS probability0.25%
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

Improper access control in Discourse before 3.4.3 and 3.5.0.beta1 through 3.5.0.beta2 allows remote authenticated users to overfill DMs. Chat::AddUsersToChannel excluded existing channel participants before evaluating the maximum-user policy, so repeated additions were checked only against newly supplied users. A user who has joined a direct-message channel can add participants beyond the configured limit, potentially placing every site user in one conversation and consuming service resources.

The record

CVE
CVE-2025-32376
Published
Apr 30, 2025
Updated
Apr 30, 2025
Vendor
Discourse
Product
Discourse
Classifications
CWE-284
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Apr 30, 2025CVE publishedPublication date reported by the CVE source.
  2. Apr 30, 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=< 3.4.3
  2. Affected versionversion=>= 3.5.0.beta1, < 3.5.0.beta3

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Discourse · Discourseversion=< 3.4.3; version=>= 3.5.0.beta1, < 3.5.0.beta3

Published CVSS scores

4.8GitHub CNACVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:A/VC:N/VI:N/VA:L/SC:N/SI:N/SA:L

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

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