CVE-2026-75588 | BDVDB-2026-375720 Detail

MattermostMattermost

Description#

Mattermost Desktop App versions <=6.2 6.2.2.0 fail to validate the URL scheme when checking whether a target URL is internal to the connected server, which allows a network-positioned attacker to load a plugin popout window over an insecure connection via a link using a downgraded URL scheme. Mattermost Advisory ID: MMSA-2026-00717

Impact#

Per CVSS v3.1: confidentiality impact none, integrity impact low, availability impact none. Attack vector: network.

Weaknesses#

CWE-1287 Improper Validation of Specified Type of Input

References#

https://mattermost.com/security-updates

Exploit#

No public exploit known

History#

Version 12026-09-17Record published in the CVE List.

Published

Published: 2026-09-17
Last modified: 2026-09-17

Vendor information

Vendor: Mattermost
Product: Mattermost

All Mattermost vulnerabilities

Score

2.6 Low

EPSS

less than 1%, Very Low

Estimated chance of exploitation in the next 30 days. EPSS percentile: 13.2.

KEV

Not listed in the CISA Known Exploited Vulnerabilities catalog.

Impact

Not classified

Action

No specific action is recorded in the source data. Check the references for vendor guidance.

Affected Systems

Vulnerable
<= 6.2.2
Fixed
Not stated
Vulnerable
Not stated
Fixed
6.3.0
Vulnerable
Not stated
Fixed
6.2.3.0

Scoring System

CVSS v4.0

Not available

CVSS v3.1

2.6 Low

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

Metric breakdown
Attack Vector	Network
Attack Complexity	High
Privileges Required	Low
User Interaction	Required
Scope	Unchanged
Confidentiality	None
Integrity	Low
Availability	None

CVSS v3.0

Not available

CVSS v2

Not available

Source: CVE List v5 (record); CISA KEV (kev, action); FIRST EPSS (epss).