Mattermost has a Path Traversal issue

CVE-2026-4858 → View on GitHub ↗ View on CVE.org ↗ View on NVD ↗

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 check integration URL for path traversal which allows an malicious authenticated user to call an arbitrary API via system admin Mattermost auth token using via path traversal in integration action URL. Mattermost Advisory ID: MMSA-2026-00640.

Basic information

Type
reviewed
Severity
high
Advisory on GitHub
Open advisory ↗
Repository advisory
—
Source code
Browse source ↗
Published (advisory)
2026-05-21 09:32:12 UTC
Updated
2026-06-23 22:02:07 UTC
GitHub reviewed
2026-06-23 22:02:06 UTC
NVD published
2026-05-21

EPSS Score

Score Percentile
0.25% 15.96%

CVSS Scores

Base score Version Severity Vector
8.0 3.1 —
CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:H/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:L)
A normal user session is enough; they don’t have to be admin.
User interaction (UI:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:C)
Breaking this can reach past the original component and bite other resources—bigger blast radius.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.

Identifiers

Type Value
GHSA GHSA-c4r7-j7pp-r8mp ↗
CVE CVE-2026-4858 ↗

CWEs

CWE id Name
CWE-22 Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')

Affected packages (4)

Vulnerable version ranges and first patched releases as published by GitHub.

Ecosystem Package Vulnerable range First patched Vulnerable functions
go github.com/mattermost/mattermost-server = 11.6.0 11.6.1 —
go github.com/mattermost/mattermost-server >= 11.5.0, < 11.5.4 11.5.4 —
go github.com/mattermost/mattermost-server >= 11.4.0, < 11.4.5 11.4.5 —
go github.com/mattermost/mattermost-server >= 10.11.0, < 10.11.15 10.11.15 —

References

cvelogic Threat Intelligence