CVE•Published 2026-05-21•Modified 2026-05-21•1 article on news•7 live references•NVD data

CVE-2026-4858Mattermost · Mattermost_server

Vulnerability data via NVD (ingested)

CVSS v3.1

8.0

HIGH

CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:H/A:H

EPSS percentile

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Weaknesses (CWE)

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

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

Timeline

Published 2026-05-21

Modified 2026-05-21

External references

NVD MITRE Exploit-DB GitHub PoC Sploitus trickest/cve VulnCheck

Search for exposed instances

Shodan + Censys queries derived from NVD's CPE data. The vuln tag catches assets Shodan has explicitly linked to this CVE; the product / banner fingerprints find exposed instances even when the vuln tag was never applied (which is common).

Shodan · vuln tag0 hosts

vuln:CVE-2026-4858

Hosts Shodan has explicitly fingerprinted as vulnerable.

Shodan · product

product:"Mattermost Mattermost Server"

All exposed Mattermost Mattermost Server instances — cross-reference with the CVE's affected-version range.

Shodan · banner/body mention

http.html:"Mattermost Server"

HTTP body or banner mentions "Mattermost Server" — catches deploys Shodan didn't identify as a product.

More intel sources (5)

Shodan report

vuln:CVE-2026-4858