CVE-2026-20719Network attack vector

Client crash via external SVG link embeds

Published Mar 25, 2026 · Updated Mar 25, 2026

Denial of service in affected Mattermost 10.11, 11.2, 11.3, and 11.4 releases allows attackers to crash web and desktop clients via SVG link embeds. The link-preview renderer accepts external SVGs referenced by GitHub issue or pull-request embeds and renders them without blocking that exceptional content type. The gate is control of a GitHub issue or pull request selected for a link embed; the reported consequence is a client crash, not server termination.

CVSS severity4.3
Medium
EPSS probability0.35%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

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Summary

What happened

Denial of service in affected Mattermost 10.11, 11.2, 11.3, and 11.4 releases allows attackers to crash web and desktop clients via SVG link embeds. The link-preview renderer accepts external SVGs referenced by GitHub issue or pull-request embeds and renders them without blocking that exceptional content type. The gate is control of a GitHub issue or pull request selected for a link embed; the reported consequence is a client crash, not server termination.

The record

CVE
CVE-2026-20719
Published
Mar 25, 2026
Updated
Mar 25, 2026
Vendor
Mattermost
Product
Mattermost
Classifications
CWE-754, T1499.004
Attack vector
network
Privileges
Unavailable

Timeline

How it unfolded

  1. Mar 25, 2026CVE publishedPublication date reported by the CVE source.
  2. Mar 25, 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=10.11.0 <=10.11.11
  2. Affected versionversion=11.2.0 <=11.2.3
  3. Affected versionversion=11.3.0 <=11.3.1
  4. Affected versionversion=11.4.0 <=11.4.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesUnavailable in this record.

What is affected?

Mattermost · Mattermostversion=10.11.0 <=10.11.11; version=11.2.0 <=11.2.3; version=11.3.0 <=11.3.1; version=11.4.0 <=11.4.0

Published CVSS scores

4.3Mattermost, Inc.CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L
7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

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 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
PrivilegesUnavailable
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-754Improper Check for Unusual or Exceptional Conditions
T1499.004Application or System Exploitation

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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