CVE-2026-2456 — Memory Allocation with Excessive Size Value in Mattermost Mattermost-server

CWE-789 — Memory Allocation with Excessive Size Value6 documents5 sources
Severity
5.7MEDIUMNVD
CNA5.3
EPSS
0.0%
top 89.43%
CISA KEV
Not in KEV
Exploit
No known exploits
Affected products
4
Github.com Mattermost Mattermost-serverGithub.com Mattermost Mattermost Server V8Mattermost Server+1 more
Timeline
PublishedMar 16
Latest updateMar 26

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

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:N/A:HExploitability: 2.1 | Impact: 3.6

Affected Packages4 packages

▶NVDmattermost/mattermost_server10.11.0 — 10.11.11+2
▶Gogithub.com/mattermost_mattermost-server10.11.0-rc1+incompatible — 10.11.11+incompatible+6
▶Gogithub.com/mattermost_mattermost_server_v8< 8.0.0-20260127165411-fe3052073dc6
▶CVEListV5mattermost/mattermost11.3.0 — 11.3.0+2

🔴Vulnerability Details

4
OSV
Mattermost fails to limit the size of responses from integration action endpoints in github.com/mattermost/mattermost-server↗2026-03-26
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CVEList
Denial of Service via Unbounded Memory Allocation in Integration Actions↗2026-03-16
▶
OSV
Mattermost fails to limit the size of responses from integration action endpoints↗2026-03-16
▶
GHSA
Mattermost fails to limit the size of responses from integration action endpoints↗2026-03-16
▶

🕵️Threat Intelligence

1
Wiz
CVE-2026-2456 Impact, Exploitability, and Mitigation Steps | Wiz↗
▶
CVE-2026-2456 — MEDIUM severity | cvebase