CVE-2026-3590
Race Condition in Guest Magic Link Authentication Allows Token Reuse
Description
Mattermost versions 10.11.x <= 10.11.12, 11.5.x <= 11.5.0, 11.4.x <= 11.4.2, 11.3.x <= 11.3.2 fail to enforce atomic single-use consumption of guest magic link tokens, which allows an attacker with access to a valid magic link to establish multiple independent authenticated sessions via concurrent requests.. Mattermost Advisory ID: MMSA-2026-00624
INFO
Published Date :
April 15, 2026, 11 a.m.
Last Modified :
April 15, 2026, 11 a.m.
Remotely Exploit :
Yes !
Source :
Mattermost
Affected Products
The following products are affected by CVE-2026-3590
vulnerability.
Even if cvefeed.io is aware of the exact versions of the
products
that
are
affected, the information is not represented in the table below.
No affected product recoded yet
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 3.1 | MEDIUM | 9302f53e-dde5-4bf3-b2f2-a83f91ac0eee | ||||
| CVSS 3.1 | MEDIUM | MITRE-CVE |
Solution
- Update Mattermost to a patched version.
- Ensure guest magic links are single-use.
- Monitor for concurrent session creation.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-3590 vulnerability anywhere in the article.