CVE-2026-3495

Unescaped variables during error page composition

CVSS 3.8 LOWEPSS 0.1%CWE-79

Vexday Risk Score

8Low

SSVC decision (CISA)

Track

No exploitation signal → monitor

CVSS 3.8EPSS 0.1%KEV nãoPoC —Nuclei —Metasploit —Patch referenciado

Lifecycle

18 May 2026Published on NVD

Recommendation: Monitor — no exploitation signal at the moment.

Mattermost versions 11.5.x <= 11.5.1, 10.11.x <= 10.11.13 fail to escape some variables that could contain malicious content during error page composition which allows an attacker with access to edit some site configuration to execute some malicious code via injecting some JS as part of those values.. Mattermost Advisory ID: MMSA-2026-00622

CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:L/I:L/A:N

Affected products

Mattermost · Mattermost

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References

https://mattermost.com/security-updates