CVE-2026-20719

Received Received - Intake

SVG Rendering Vulnerability in Mattermost Allows Denial of Service

Publication date: 2026-03-25

Last updated on: 2026-03-26

Assigner: Mattermost, Inc.

Description

Mattermost versions 11.4.x <= 11.4.0, 11.3.x <= 11.3.1, 11.2.x <= 11.2.3, 10.11.x <= 10.11.11 fail to prevent rendering of external SVGs on link embeds which allows unauthenticated users to crash the Mattermost webapp and desktop app via creating an issue or PR on GitHub.. Mattermost Advisory ID: MMSA-2026-00595

CVSS Scores

EPSS Scores

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Meta Information

Published

2026-03-25

Last Modified

2026-03-26

Generated

2026-07-06

AI Q&A

2026-03-25

EPSS Evaluated

2026-07-05

NVD

CVE-2026-20719

EUVD

EUVD-2026-15485

Affected Vendors & Products

Vendor	Product	Version / Range
mattermost	mattermost_server	From 10.11.0 (inc) to 10.11.12 (exc)
mattermost	mattermost_server	From 11.2.0 (inc) to 11.2.4 (exc)
mattermost	mattermost_server	From 11.3.0 (inc) to 11.3.2 (exc)
mattermost	mattermost_server	From 11.4.0 (inc) to 11.4.1 (exc)

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-754	The product does not check or incorrectly checks for unusual or exceptional conditions that are not expected to occur frequently during day to day operation of the product.

Attack-Flow Graph

Executive Summary

This vulnerability affects certain versions of Mattermost (11.4.x <= 11.4.0, 11.3.x <= 11.3.1, 11.2.x <= 11.2.3, 10.11.x <= 10.11.11) where the application fails to prevent rendering of external SVG files on link embeds.

Because of this failure, unauthenticated users can exploit this by creating an issue or pull request on GitHub that includes such SVGs, which causes the Mattermost web and desktop applications to crash.

Impact Analysis

The impact of this vulnerability is a denial of service condition where the Mattermost webapp and desktop app can be crashed by unauthenticated users.

This could disrupt communication and collaboration within an organization using the affected Mattermost versions.

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