CVE-2025-55074Network attack vector

Read-status disclosure via unsanitized member timestamps

Published Nov 18, 2025 · Updated Nov 18, 2025

Information disclosure in Mattermost 10.5.0 through 10.5.11 and 10.11.0 through 10.11.3 allows remote authenticated users to infer channel reads. The channel-member API returns other users' LastViewedAt and LastUpdateAt timestamps without applying per-user response sanitization. A low-privileged account must share relevant channel access, and another user's channel activity must supply the timestamps, exposing read timing only.

CVSS severity3.0
Low
EPSS probability0.17%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Information disclosure in Mattermost 10.5.0 through 10.5.11 and 10.11.0 through 10.11.3 allows remote authenticated users to infer channel reads. The channel-member API returns other users' LastViewedAt and LastUpdateAt timestamps without applying per-user response sanitization. A low-privileged account must share relevant channel access, and another user's channel activity must supply the timestamps, exposing read timing only.

The record

CVE
CVE-2025-55074
Published
Nov 18, 2025
Updated
Nov 18, 2025
Vendor
Mattermost
Product
Mattermost
Classifications
CWE-1426, CWE-276, T1213.005
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Nov 18, 2025CVE publishedPublication date reported by the CVE source.
  2. Nov 18, 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=10.11.0 <=10.11.3
  2. Affected versionversion=10.5.0 <=10.5.11

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Mattermost · Mattermostversion=10.11.0 <=10.11.3; version=10.5.0 <=10.5.11

Published CVSS scores

3.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:N/A:N
3.0Mattermost, Inc.CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:L/I:N/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.

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-1426Improper Validation of Generative AI Output
CWE-276Incorrect Default Permissions
T1213.005Data from Information Repositories: Messaging Applications

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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