PT-2026-27989 · Mattermost · Mattermost

Christopher Poile · Publicado 2026-03-25 · Atualizado 2026-03-25 · CVE-2026-27656

Positive Technologies (AI Summary)

CVSS v3.1

6.1

Média

Vetor base

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

Name of the Vulnerable Software and Affected Versions Mattermost versions 11.4.0 and earlier, 11.3.1 and earlier, 11.2.3 and earlier, 10.11.11 and earlier

Description The software does not properly validate user identity within the OpenID IsSameUser() comparison logic. This flaw, stemming from overly permissive substring matching in the user discovery flow, could allow an attacker to compromise user accounts.

Recommendations Update Mattermost to a version later than 11.4.0. Update Mattermost to a version later than 11.3.1. Update Mattermost to a version later than 11.2.3. Update Mattermost to a version later than 10.11.11.

Correção

Enumeração de Fraquezas

CWE-303

Identificadores relacionados

CVE-2026-27656

GHSA-FG35-5RF6-QG3G

Produtos afetados

Mattermost

Referências · 6

• https://github.com/mattermost/mattermost · Nota
• https://mattermost.com/security-updates · Aviso do Fabricante
• https://osv.dev/vulnerability/GHSA-fg35-5rf6-qg3g · Aviso do Fabricante
• https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2026-27656 · Nota
• https://twitter.com/CVEnew/status/2036911848105402670 · Publicação no Twitter
• https://nvd.nist.gov/vuln/detail/CVE-2026-27656 · Nota de Segurança