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Description

Mattermost versions 11.3.x <= 11.3.0, 11.2.x <= 11.2.2, 10.11.x <= 10.11.10 Mattermost fails to limit the size of responses from integration action endpoints, which allows an authenticated attacker to cause server memory exhaustion and denial of service via a malicious integration server that returns an arbitrarily large response when a user clicks an interactive message button.. Mattermost Advisory ID: MMSA-2026-00571

PUBLISHED Reserved 2026-02-13 | Published 2026-03-16 | Updated 2026-03-16 | Assigner Mattermost




MEDIUM: 5.3CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:N/A:H

Problem types

CWE-789: Memory Allocation with Excessive Size Value

Product status

Default status
unaffected

11.3.0 (semver)
affected

11.2.0 (semver)
affected

10.11.0 (semver)
affected

11.4.0
unaffected

11.3.1
unaffected

11.2.3
unaffected

10.11.11
unaffected

Credits

Daniel Espino Garcia finder

References

mattermost.com/security-updates (MMSA-2026-00571) vendor-advisory

cve.org (CVE-2026-2456)

nvd.nist.gov (CVE-2026-2456)

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