CVE-2025-9076Network attack vector

Sensitive user-data disclosure via unsanitized membership objects

Published Sep 15, 2025 · Updated Sep 15, 2025

Missing authorization in shared-channel sync in Mattermost 10.10.0 through 10.10.1 allows remote authenticated users to read sensitive user data. syncMembershipBatchToRemotes inserts each original user object into the outgoing SyncMsg instead of copying and sanitizing it. Exploitation requires shared channels and control of a connected remote cluster; the receiving cluster obtains protected fields from synchronized users.

CVSS severity6.5
Medium
EPSS probability0.26%
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 shared-channel sync in Mattermost 10.10.0 through 10.10.1 allows remote authenticated users to read sensitive user data. syncMembershipBatchToRemotes inserts each original user object into the outgoing SyncMsg instead of copying and sanitizing it. Exploitation requires shared channels and control of a connected remote cluster; the receiving cluster obtains protected fields from synchronized users.

The record

CVE
CVE-2025-9076
Published
Sep 15, 2025
Updated
Sep 15, 2025
Vendor
Mattermost
Product
Mattermost
Classifications
CWE-862, T1213
Attack vector
network
Privileges
admin

Timeline

How it unfolded

  1. Sep 15, 2025CVE publishedPublication date reported by the CVE source.
  2. Sep 15, 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=10.10.0 <=10.10.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesadmin

What is affected?

Mattermost · Mattermostversion=10.10.0 <=10.10.1

Published CVSS scores

6.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
6.5Mattermost, Inc.CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/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
Privilegesadmin
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-862Missing Authorization
T1213Data from Information Repositories

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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