5.7

CVE-2026-2456: Denial of Service via Unbounded Memory Allocation in Integration Actions

Analyzed
AliasesGHSA-34g8-9fpp-46chGO-2026-4726
Published 16-03-2026Last modified 16-03-2026

Vulnerability summary

CVE-2026-2456 is a medium (CVSS 5.7) vulnerability in mattermost. EPSS estimates a 0.17% chance of exploitation in the next 30 days, higher than 6.5% of scored vulnerabilities.

Priority
Routine

Not severe (CVSS 5.3, network access); no exploitation reported by the 5 checked sources

Source freshness unavailable

How is this decided?
CVSS score
5.7/10
010
Medium · v3.1 (NVD)
EPSS score
0.17%
0%100%
Low · +0.01 pp in 30 days
KEVNot listedNot listed by any tracked catalog.
RansomwareNot flaggedNo ransomware use recorded.
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 2 · Related 2
OPENSUSE-SU-2026:21483-1SUSE-SU-2026:1135-1

Timeline

  1. 16-03-2026
    PublishedVulnerability first disclosed.
  2. 16-03-2026
    Last modifiedVulnerability information updated.

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 metrics

3 scores · 3 sources · 1 version

EPSS trend

Probability

0.17%

Chance of exploitation in the next 30 days

Percentile

7%

Versus all other CVEs

30-day change

Increase +0.01 pp

From 0.17% on 04-10-2026

04-10-202603-11-2026

Known exploited

Compare KEV catalogs
CISA KEV

Not in the CISA KEV catalog.

ENISA CNW

Not in the ENISA CNW catalog.

CIRCL

Not in the CIRCL catalog.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Version check

Known conditions: network-reachable, no authentication, user interaction (CVSS vector). Other conditions: not stated in public data.

Github.com/mattermost/mattermost-server2 products
  • v5All versions (No fix recorded)
  • v6All versions (No fix recorded)
Mattermost2 products
  • mattermost11.3.0 | ≥ 11.2.0, ≤ 11.2.2 | ≥ 10.11.0, ≤ 10.11.10
  • mattermost_server≥ 10.11.0, < 10.11.11 | ≥ 11.2.0, < 11.2.3 | ≥ 11.3.0, < 11.3.1
Github.com/mattermost1 product
  • mattermost-server< 5.3.2-0.20260127165411-fe3052073dc6 | ≥ 10.11.0-rc1, < 10.11.11 | ≥ 11.2.0-rc1, < 11.2.3 | ≥ 11.3.0-rc1, < 11.3.1 | ≥ 11.3.0-rc1+incompatible, < 11.3.1+incompatible
Github.com/mattermost/mattermost/server1 product
  • v8< 8.0.0-20260127165411-fe3052073dc6

4 vendors · 6 products

References

5 links