#VU106103 Race condition in Discourse - CVE-2025-24808

Vulnerability identifier: #VU106103

Vulnerability risk: Medium

CVSSv4.0: 1.3 [CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:U/U:Green]

CVE-ID: CVE-2025-24808

CWE-ID: CWE-362

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
Discourse
Web applications / Forum & blogging software

Vendor: Civilized Discourse Construction Kit, Inc.

Description

The vulnerability allows a remote attacker to compromise the target system.

The vulnerability exists due to a race condition when adding users to a group DM. A remote user can exploit the race and send requests to add new users in parallel ignoring the limit.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Discourse: 3.3.0 beta1 - 3.4.0 beta4

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External links
https://github.com/discourse/discourse/commit/a16b2f224860f6678f89f5ffa012f0ede17e4095
https://github.com/discourse/discourse/security/advisories/GHSA-hfcx-qjw6-573r

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Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote authenticated user via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.