TI-2025-18525 Aliases CVE-2025-24808

Discourse has race condition when adding users to a group DM

LOW 19CWE-362Published 2025-03-26 · Updated 2025-03-26

Key facts

Attack vector: Network
Privileges required: Low
User interaction: None
Attack complexity: Low
Impact type: —
Confidentiality · integrity · availability: None · Low · None
Fix status: Fixed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA.

Summary

Discourse is an open-source discussion platform. Prior to versions `3.3.4` on the `stable` branch and `3.4.0.beta5` on the `beta` branch, someone who is about to reach the limit of users in a group DM may send requests to add new users in parallel. The requests might all go through ignoring the limit due to a race condition. The patch in versions `3.3.4` and `3.4.0.beta5` uses the `lock` step in service to wrap part of the `add_users_to_channel` service inside a distributed lock/mutex in order to avoid the race condition.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV

EPSS 0.00218 12th percentileScored 2026-11-07

Fix Fixed discourse (discourse): 3.3.4, 3.4.0.beta5

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation: None
Automatable: No
Technical impact: Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

Vendor	Product	Affected versions	Fixed in	Status	Source
discourse	discourse	before 3.3.4; 3.4.0.beta1 to before 3.4.0.beta5	3.3.4, 3.4.0.beta5	Patch available	CNA

discourse Vendordiscourse Affected before 3.3.4; 3.4.0.beta1 to before 3.4.0.beta5 Fixed in 3.3.4, 3.4.0.beta5 Patch available CNA

CPE configurations NVD · 6

CPE	Versions	Role	Vendor
cpe:2.3:a:discourse:discourse:::::stable:::*	before 3.3.3	Vulnerable	discourse
cpe:2.3:a:discourse:discourse:::::beta:::*	before 3.4.0	Vulnerable	discourse
cpe:2.3:a:discourse:discourse:3.4.0:beta1:::beta:::*	3.4.0 beta1	Vulnerable	discourse
cpe:2.3:a:discourse:discourse:3.4.0:beta2:::beta:::*	3.4.0 beta2	Vulnerable	discourse
cpe:2.3:a:discourse:discourse:3.4.0:beta3:::beta:::*	3.4.0 beta3	Vulnerable	discourse
cpe:2.3:a:discourse:discourse:3.4.0:beta4:::beta:::*	3.4.0 beta4	Vulnerable	discourse

cpe:2.3:a:discourse:discourse:*:*:*:*:stable:*:*:* Versions before 3.3.3 Vulnerable ·discourse
cpe:2.3:a:discourse:discourse:*:*:*:*:beta:*:*:* Versions before 3.4.0 Vulnerable ·discourse
cpe:2.3:a:discourse:discourse:3.4.0:beta1:*:*:beta:*:*:* Versions 3.4.0 beta1 Vulnerable ·discourse
cpe:2.3:a:discourse:discourse:3.4.0:beta2:*:*:beta:*:*:* Versions 3.4.0 beta2 Vulnerable ·discourse
cpe:2.3:a:discourse:discourse:3.4.0:beta3:*:*:beta:*:*:* Versions 3.4.0 beta3 Vulnerable ·discourse
cpe:2.3:a:discourse:discourse:3.4.0:beta4:*:*:beta:*:*:* Versions 3.4.0 beta4 Vulnerable ·discourse

Remediation

Fix · CNA discourse (discourse) Fixed in 3.3.4, 3.4.0.beta5

Timeline

2026-10-02 Threatist record created from CVE-2025-24808

References

Patch 1

https://github.com/discourse/discourse/commit/a16b2f224860f6678f89f5ffa012f0ede17e4095

Advisory 1

https://github.com/discourse/discourse/security/advisories/GHSA-hfcx-qjw6-573r

TI-2021-19656 Denial of Service in discourse CVSS 3.1MEDIUM 6.8
TI-2024-36150 Potential Backup file leaked via Nginx in Discourse CVSS 3.1HIGH 7.5
TI-2021-18002 RCE via malicious SNS subscription payload CVSS 3.1CRITICAL 10.0
TI-2026-24651 Discourse: Open redirect via `sso_destination_url` cookie in `enter` CVSS 4.0MEDIUM 5.1
TI-2026-22278 Discourse leaks private topic title and post excerpt via user action API endpoint CVSS 4.0HIGH 8.7
TI-2023-24152 Unauthenticated access to new private chat messages in Discourse CVSS 3.1HIGH 7.5

See all 262 →

Sources

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