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Vulnerability Details :

CVE-2026-3471

Summary
Assigner-Mattermost
Assigner Org ID-9302f53e-dde5-4bf3-b2f2-a83f91ac0eee
Published At-18 May, 2026 | 08:45
Updated At-18 May, 2026 | 14:35
Rejected At-
Credits

Opening a window with {{javascript:alert()}} as URL causes crash in the Mattermost Desktop App

Mattermost Desktop App versions <=6.1 6.0.1 5.4.13.0 fail to prevent an invalid URL from loading in a pop-up window in the Mattermost Desktop App which allows a malicious server owner to repeated crash the application via calling {{window.open('javascript:alert()');}}. Mattermost Advisory ID: MMSA-2026-00618

Vendors
-
Not available
Products
-
Metrics (CVSS)
VersionBase scoreBase severityVector
Weaknesses
Attack Patterns
Solution/Workaround
References
HyperlinkResource Type
EPSS History
Score
Latest Score
-
N/A
No data available for selected date range
Percentile
Latest Percentile
-
N/A
No data available for selected date range
Stakeholder-Specific Vulnerability Categorization (SSVC)
▼Common Vulnerabilities and Exposures (CVE)
cve.org
Assigner:Mattermost
Assigner Org ID:9302f53e-dde5-4bf3-b2f2-a83f91ac0eee
Published At:18 May, 2026 | 08:45
Updated At:18 May, 2026 | 14:35
Rejected At:
▼CVE Numbering Authority (CNA)
Opening a window with {{javascript:alert()}} as URL causes crash in the Mattermost Desktop App

Mattermost Desktop App versions <=6.1 6.0.1 5.4.13.0 fail to prevent an invalid URL from loading in a pop-up window in the Mattermost Desktop App which allows a malicious server owner to repeated crash the application via calling {{window.open('javascript:alert()');}}. Mattermost Advisory ID: MMSA-2026-00618

Affected Products
Vendor
Mattermost, Inc.Mattermost
Product
Mattermost
Default Status
unaffected
Versions
Affected
  • From 0 through 6.0.1 (semver)
  • From 0 through 5.4.13 (semver)
Unaffected
  • 6.2.0
  • 6.1.1.0
  • 5.13.5.0
Problem Types
TypeCWE IDDescription
CWECWE-939CWE-939: Improper Authorization in Handler for Custom URL Scheme
Type: CWE
CWE ID: CWE-939
Description: CWE-939: Improper Authorization in Handler for Custom URL Scheme
Metrics
VersionBase scoreBase severityVector
3.16.5MEDIUM
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
Version: 3.1
Base score: 6.5
Base severity: MEDIUM
Vector:
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
Metrics Other Info
Impacts
CAPEC IDDescription
Solutions

Update Mattermost Desktop App to versions 6.2.0, 6.1.1.0, 5.13.5.0 or higher.

Configurations
Workarounds
Exploits
Credits
finder
game0v3r
Timeline
EventDate
Replaced By
Rejected Reason
References
HyperlinkResource
https://mattermost.com/security-updates
vendor-advisory
Hyperlink: https://mattermost.com/security-updates
Resource:
vendor-advisory
▼Authorized Data Publishers (ADP)
CISA ADP Vulnrichment
Affected Products
Metrics
VersionBase scoreBase severityVector
Metrics Other Info
Impacts
CAPEC IDDescription
Solutions
Configurations
Workarounds
Exploits
Credits
Timeline
EventDate
Replaced By
Rejected Reason
References
HyperlinkResource
Information is not available yet
▼National Vulnerability Database (NVD)
nvd.nist.gov
Source:responsibledisclosure@mattermost.com
Published At:18 May, 2026 | 09:16
Updated At:18 May, 2026 | 17:32

Mattermost Desktop App versions <=6.1 6.0.1 5.4.13.0 fail to prevent an invalid URL from loading in a pop-up window in the Mattermost Desktop App which allows a malicious server owner to repeated crash the application via calling {{window.open('javascript:alert()');}}. Mattermost Advisory ID: MMSA-2026-00618

CISA Catalog
Date AddedDue DateVulnerability NameRequired Action
N/A
Date Added: N/A
Due Date: N/A
Vulnerability Name: N/A
Required Action: N/A
Metrics
TypeVersionBase scoreBase severityVector
Secondary3.16.5MEDIUM
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
Type: Secondary
Version: 3.1
Base score: 6.5
Base severity: MEDIUM
Vector:
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
CPE Matches
Weaknesses
CWE IDTypeSource
CWE-939Secondaryresponsibledisclosure@mattermost.com
CWE ID: CWE-939
Type: Secondary
Source: responsibledisclosure@mattermost.com
Evaluator Description
Evaluator Impact

Evaluator Solution

Vendor Statements
References
HyperlinkSourceResource
https://mattermost.com/security-updatesresponsibledisclosure@mattermost.com
N/A
Hyperlink: https://mattermost.com/security-updates
Source: responsibledisclosure@mattermost.com
Resource: N/A

Change History

0
Information is not available yet

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Details not found