PT-2026-33054 · Mattermost · Mattermost

Published 2026-04-15 · Updated 2026-04-17 · CVE-2026-3590

Positive Technologies (AI Summary)

CVSS v3.1

6.5

Medium

Base vector

AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

Name of the Vulnerable Software and Affected Versions Mattermost versions 10.11.0 through 10.11.12 Mattermost version 11.5.0 Mattermost versions 11.4.0 through 11.4.2 Mattermost versions 11.3.0 through 11.3.2

Description Failure to enforce atomic single-use consumption of guest magic link tokens allows an attacker with access to a valid magic link to establish multiple independent authenticated sessions by sending concurrent requests.

Recommendations At the moment, there is no information about a newer version that contains a fix for this vulnerability.

Time Of Check To Time Of Use

Weakness Enumeration

CWE-367

Related Identifiers

BDU:2026-05568

CVE-2026-3590

GHSA-MH4X-RMRX-3HP4

Affected Products

Mattermost

References · 8

• https://mattermost.com/security-updates · Vendor Advisory
• https://bdu.fstec.ru/vul/2026-05568 · Security Note
• https://osv.dev/vulnerability/GHSA-mh4x-rmrx-3hp4 · Vendor Advisory
• https://nvd.nist.gov/vuln/detail/CVE-2026-3590 · Security Note
• https://github.com/mattermost/mattermost · Note
• https://twitter.com/VulmonFeeds/status/2044464372378952054 · Twitter Post
• https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2026-3590 · Note
• https://twitter.com/CVEnew/status/2044737988303716378 · Twitter Post