CVE-2026-1628Network attack vector

Preload functionality exposure via unguarded external navigation

Published Mar 2, 2026 · Updated Mar 2, 2026

CWE-829 in Mattermost Desktop App 5.13.3 and earlier allows remote attackers to expose preload APIs via a crafted external link. Desktop window creation fails to attach navigation listeners, so linked external content opens inside an Electron renderer that retains the app preload bridge. Exploitation requires a victim to connect to a malicious Mattermost server and open its external link, enabling untrusted site code to invoke exposed preload functionality.

CVSS severity4.6
Medium
EPSS probability0.14%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

CWE-829 in Mattermost Desktop App 5.13.3 and earlier allows remote attackers to expose preload APIs via a crafted external link. Desktop window creation fails to attach navigation listeners, so linked external content opens inside an Electron renderer that retains the app preload bridge. Exploitation requires a victim to connect to a malicious Mattermost server and open its external link, enabling untrusted site code to invoke exposed preload functionality.

The record

CVE
CVE-2026-1628
Published
Mar 2, 2026
Updated
Mar 2, 2026
Vendor
Mattermost
Product
Mattermost
Classifications
CWE-829, T1204.001
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Mar 2, 2026CVE publishedPublication date reported by the CVE source.
  2. Mar 2, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <=5.13.3

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Mattermost · Mattermostversion=0 <=5.13.3

Published CVSS scores

4.6Mattermost, Inc.CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:L/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-829Inclusion of Functionality from Untrusted Control Sphere
T1204.001Malicious Link

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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