Calling window.close() from server-side content causes crash in the Mattermost Desktop App
Published May 18, 2026
3.5
LOWCVSS 3.1
EPSS 0.29%
Description
Mattermost Desktop App versions <=6.1 6.0.1 5.4.13.0 fail to prevent server-rendered content from closing an underlying application view in the Mattermost Desktop App which allows a malicious server or plugin to crash the desktop client via invoking {{window.close()}} in the renderer context, leading to a denial of service condition at the client level. Mattermost Advisory ID: MMSA-2026-00633
Affected products
-
- Version 0StatusaffectedConstraints<=5.4.13
- Version 0StatusaffectedConstraints<=6.0.1
- Version 5.13.5.0StatusunaffectedConstraints-
- Version 6.1.1.0StatusunaffectedConstraints-
- Version 6.2.0StatusunaffectedConstraints-
- Version
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
| Vendor | Product | Default status | Versions | ||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Mattermost | Mattermost | unaffected |
|
- ≤ 5.4.13.0
- ≥ 6.0.0 · ≤ 6.0.1
- ≥ 6.1.0 · < 6.2.0
No data.
No Red Hat product state for this CVE.
No package ranges for this CVE.
Remediation
Vendor solution
Update Mattermost Desktop App to versions 6.2.0, 6.1.1.0, 5.13.5.0 or higher.
Metrics
No CVSS v4.0 score for this CVE.
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:N/A:L
No CVSS v3.0 score for this CVE.
No CVSS v2.0 score for this CVE.
This CVE is not in the KEV list.
CISA SSVC (Vulnrichment)
Stakeholder-Specific Vulnerability Categorization from CISA ADP.
Exploitation
NoneAutomatable
NoTechnical Impact
PartialDecision
n/aAssessed May 18, 2026 · SSVC 2.0.3
Estimated probability of exploitation in the wild in the next 30 days (FIRST EPSS). As of Oct 1, 2026.
Score over time
May–Oct 2026- EPSS v4
- EPSS v5
Percentile over time
- EPSS v4
- EPSS v5
Table of values (3 key points)
Flat stretches are collapsed; showing up to 120 newest points.
| Date | Score | Percentile | Model |
|---|---|---|---|
| Oct 1, 2026 | 0.29% (0.00288) | 19.24th | v5 (v2026.06.15) |
| Jun 15, 2026 | 0.17% (0.00171) | 6.67th | v5 (v2026.06.15) |
| May 19, 2026 | 0.03% (0.00033) | 9.59th | v4 (v2025.03.14) |
References (1)
- https://mattermost.com/security-updates vendor-advisoryVendor Advisory
| Link | Providers | Tags |
|---|---|---|
| https://mattermost.com/security-updates | vendor-advisoryVendor Advisory |
Change history (0)
No recorded changes yet.