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Description

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

PUBLISHED Reserved 2026-03-03 | Published 2026-05-18 | Updated 2026-05-18 | Assigner Mattermost




LOW: 3.8CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:L/I:L/A:N

Problem types

CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

Product status

Default status
unaffected

11.5.0 (semver)
affected

10.11.0 (semver)
affected

11.6.0
unaffected

11.5.2
unaffected

10.11.14
unaffected

Credits

shoodagiri finder

References

mattermost.com/security-updates (MMSA-2026-00622) vendor-advisory

cve.org (CVE-2026-3495)

nvd.nist.gov (CVE-2026-3495)

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