CVE-2026-3590
Magic Link Token Replay Vulnerability in Mattermost Authentication
Publication date: 2026-04-15
Last updated on: 2026-04-22
Assigner: Mattermost, Inc.
Description
Description
CVSS Scores
EPSS Scores
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Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| mattermost | mattermost_server | From 10.11.0 (inc) to 10.11.13 (exc) |
| mattermost | mattermost_server | From 11.3.0 (inc) to 11.3.3 (exc) |
| mattermost | mattermost_server | From 11.4.0 (inc) to 11.4.3 (exc) |
| mattermost | mattermost_server | From 11.5.0 (inc) to 11.5.1 (exc) |
Helpful Resources
Exploitability
| CWE ID | Description |
|---|---|
| CWE-367 | The product checks the state of a resource before using that resource, but the resource's state can change between the check and the use in a way that invalidates the results of the check. |
Attack-Flow Graph
AI Powered Q&A
How can this vulnerability impact me? :
The vulnerability allows an attacker to reuse a single valid guest magic link multiple times to create multiple authenticated sessions.
This can lead to unauthorized access and potential misuse of guest accounts, increasing the risk of data exposure or unauthorized actions within the Mattermost environment.
Can you explain this vulnerability to me?
This vulnerability exists in certain versions of Mattermost where the system fails to enforce atomic single-use consumption of guest magic link tokens.
Because of this failure, an attacker who has access to a valid magic link can use it multiple times concurrently to establish multiple independent authenticated sessions.