CVE-2025-20033Network attack vector

Plugin-reader disruption via unvalidated custom post props

Published Jan 9, 2025 · Updated Jan 9, 2025

Improper post-type validation in Mattermost allows remote authenticated users to interrupt plugin-reader sessions with crafted posts. The post-creation path accepts the custom_pl_notification type with specially shaped props, causing the affected reader to process a server-reserved notification as trusted data. A low-privileged account can submit the crafted post over the network, and only users granted sysconsole_read_plugins are disrupted.

CVSS severity4.3
Medium
EPSS probability0.62%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper post-type validation in Mattermost allows remote authenticated users to interrupt plugin-reader sessions with crafted posts. The post-creation path accepts the custom_pl_notification type with specially shaped props, causing the affected reader to process a server-reserved notification as trusted data. A low-privileged account can submit the crafted post over the network, and only users granted sysconsole_read_plugins are disrupted.

The record

CVE
CVE-2025-20033
Published
Jan 9, 2025
Updated
Jan 9, 2025
Vendor
Mattermost
Product
Mattermost
Classifications
CWE-1287, T1499
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Jan 9, 2025CVE publishedPublication date reported by the CVE source.
  2. Jan 9, 2025Record 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=10.0.0 <=10.0.3
  2. Affected versionversion=10.1.0 <=10.1.3
  3. Affected versionversion=10.2.0
  4. Affected versionversion=9.11.0 <=9.11.5

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Mattermost · Mattermostversion=10.0.0 <=10.0.3; version=10.1.0 <=10.1.3; version=10.2.0; version=9.11.0 <=9.11.5

Published CVSS scores

4.3MattermostCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L
6.5NVDCVSS:3.1/AV:N/AC:L/PR:L/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 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-1287Improper Validation of Specified Type of Input
T1499Endpoint Denial of Service

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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