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Description

Mattermost versions 11.6.x <= 11.6.0, 11.5.x <= 11.5.3, 11.4.x <= 11.4.4, 10.11.x <= 10.11.14 fail to enforce request body size limits on plugin HTTP endpoints which allows an attacker to cause a denial of service via crafted oversized HTTP requests.. Mattermost Advisory ID: MMSA-2026-00646

PUBLISHED Reserved 2026-04-01 | Published 2026-05-22 | Updated 2026-05-22 | Assigner Mattermost




MEDIUM: 4.9CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H

Problem types

CWE-400 Uncontrolled Resource Consumption

Product status

Default status
unaffected

11.6.0 (semver)
affected

11.5.0 (semver)
affected

11.4.0 (semver)
affected

10.11.0 (semver)
affected

11.7.0
unaffected

11.6.1
unaffected

11.5.4
unaffected

11.4.5
unaffected

10.11.15
unaffected

Credits

thecybertantrik finder

References

mattermost.com/security-updates (MMSA-2026-00646) vendor-advisory

cve.org (CVE-2026-5308)

nvd.nist.gov (CVE-2026-5308)

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