CVE-2019-20869Network attack vector

Authenticated private-channel modification via missing membership check

Published Jun 19, 2020 · Updated Aug 5, 2024

Missing authorization in Mattermost Server before 5.10.0, 5.9.1, 5.8.2, and 4.10.9 allows remote authenticated users to alter private channels. The Update and Patch Channel API handlers apply changes to a private channel without first confirming that the requesting user belongs to it. A valid server account and the target channel identifier are required; exploitation changes channel metadata but does not disclose messages or interrupt service.

CVSS severity5.3
Medium
EPSS probability0.81%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Missing authorization in Mattermost Server before 5.10.0, 5.9.1, 5.8.2, and 4.10.9 allows remote authenticated users to alter private channels. The Update and Patch Channel API handlers apply changes to a private channel without first confirming that the requesting user belongs to it. A valid server account and the target channel identifier are required; exploitation changes channel metadata but does not disclose messages or interrupt service.

The record

CVE
CVE-2019-20869
Published
Jun 19, 2020
Updated
Aug 5, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
T1565.001
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Jun 19, 2020CVE publishedPublication date reported by the CVE source.
  2. Aug 5, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

5.0NVDAV:N/AC:L/Au:N/C:N/I:P/A:N
5.3NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/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.

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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

T1565.001Stored Data Manipulation

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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