CVE-2026-3471 | 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

Published: 2026-05-18 Last update: 2026-06-05 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2026-3471 is rated Low Risk (29.6/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.03%). Monitor for updates and reassess as exploit intelligence or EPSS changes.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2026-3471

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-05-19 — 0.03% —

Full EPSS history (1 record total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-3471

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
6.5 3.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 2.8 3.6 [email protected]

Weakness enumeration for CVE-2026-3471

GitHub Security Advisory for CVE-2026-3471

GHSA-fhqj-97rr-gvhp · Severity: medium — Mattermost Desktop App versions <=6.1 6.0.1 5.4.13.0 fail to prevent an invalid URL from loading...

Affected software / configurations for CVE-2026-3471

Vendor Product Version Raw CPE
mattermost mattermost_desktop <= 5.4.13.0 cpe:2.3:a:mattermost:mattermost_desktop:*:*:*:*:*:*:*:*
mattermost mattermost_desktop >= 6.0.0, <= 6.0.1 cpe:2.3:a:mattermost:mattermost_desktop:*:*:*:*:*:*:*:*
mattermost mattermost_desktop >= 6.1.0, < 6.2.0 cpe:2.3:a:mattermost:mattermost_desktop:*:*:*:*:*:*:*:*

References for CVE-2026-3471

URL Tags
https://mattermost.com/security-updates Vendor Advisory
cvelogic Threat Intelligence