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Vulnerabilities

Vulnerability · CVE-2026-3471

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 malici…

Published May 18, 2026 · catalog updated Jun 17, 2026 · mattermost desktop

Last checked Oct 25, 2026. A connected source was read within the last 7 days.

Check if you run it

No confirmed exploitation is on record for CVE-2026-3471. EPSS is 0.18%. Act only if a listed version of mattermost desktop is installed.

Gaps on this record

  • No vendor fix or required action is stored. Compare the linked advisory before you change production.

Same product and reporting

Severity
Medium6.5
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.18%
Remediation
Version ranges on file
Affected products
cpe mattermost/mattermost desktop · stated mattermost desktop

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

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • cpe mattermost/mattermost desktopversion unspecified
  • stated mattermost desktop<= 6.1

How to fix CVE-2026-3471

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-3471. EPSS is 0.18%. Act only if a listed version of mattermost desktop is installed.

Which versions are affected?

Compare what you have installed with mattermost desktop <= 6.1. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-939. EPSS 0.18%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

No public source repository is identified for this product.

Timeline

Detection, updates, and resolution for this record.

  1. May 18, 2026 · NIST NVD

    Detected

    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

  2. Jun 17, 2026 · NIST NVD

    Updated

    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

Sources

  • CVE.orgVulnerability recordCVE-2026-3471

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-3471

    30-day exploitation probability 0.18%

    first.org
  • NIST NVDVulnerability recordCVE-2026-3471

    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

    nvd.nist.gov

References

Freshness

Last verified in this catalog Oct 25, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.

  • FIRST EPSSOct 25, 2026
  • NIST NVDOct 20, 2026
  • CVE.orgOct 16, 2026