CVE-2025-20086Network attack vector

Authenticated server crash via malformed post props

Published Jan 15, 2025 · Updated Feb 12, 2025

Improper post-props validation in Mattermost 9.11.0 through 9.11.5 and 10.0.0 through 10.2.0 allows remote authenticated users to crash the server. Mattermost has not disclosed which post-props processing locus accepts the malicious value or the invalid operation that triggers the crash. Any authenticated account able to submit the crafted post can interrupt service, while no confidentiality or integrity impact is reported.

CVSS severity6.5
Medium
EPSS probability0.43%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Improper post-props validation in Mattermost 9.11.0 through 9.11.5 and 10.0.0 through 10.2.0 allows remote authenticated users to crash the server. Mattermost has not disclosed which post-props processing locus accepts the malicious value or the invalid operation that triggers the crash. Any authenticated account able to submit the crafted post can interrupt service, while no confidentiality or integrity impact is reported.

The record

CVE
CVE-2025-20086
Published
Jan 15, 2025
Updated
Feb 12, 2025
Vendor
Mattermost
Product
Mattermost
Classifications
CWE-1287, T1499
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Jan 15, 2025CVE publishedPublication date reported by the CVE source.
  2. Feb 12, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

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

6.5GitHub Security AdvisoryCVSS: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 10, 2026Sep 16, 2026
Latest reporting daySep 16, 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

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo