Mattermost allows other users to determine when users had read channels via channel member objects

Description

Mattermost versions 10.11.x <= 10.11.3, and 10.5.x <= 10.5.11 fail to enforce access permissions on the Agents plugin which allows other users to determine when users had read channels via channel member objects.

Basic information

Type
reviewed
Severity
low
Advisory on GitHub
Open advisory ↗
Repository advisory
Source code
Browse source ↗
Published (advisory)
2025-11-18 18:32:52 UTC
Updated
2025-11-27 08:34:13 UTC
GitHub reviewed
2025-11-18 21:03:28 UTC
NVD published
2025-11-18

EPSS Score

Score Percentile
0.02% 5.08%

CVSS Scores

Base score Version Severity Vector
3.0 3.1
CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:L/I:N/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:L)
A normal user session is enough; they don’t have to be admin.
User interaction (UI:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:C)
Breaking this can reach past the original component and bite other resources—bigger blast radius.
Confidentiality (C:L)
Some sensitive info could get out, but not a total data dump.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:N)
Service keeps running; no real outage angle.

Identifiers

CWEs

CWE id Name
CWE-276 Incorrect Default Permissions

Affected packages (3)

Vulnerable version ranges and first patched releases as published by GitHub.

Ecosystem Package Vulnerable range First patched Vulnerable functions
go github.com/mattermost/mattermost-server >= 10.11.0, < 10.11.4 10.11.4
go github.com/mattermost/mattermost-server >= 10.5.0, < 10.5.12 10.5.12
go github.com/mattermost/mattermost/server/v8 < 8.0.0-20250905150616-ba86dfc5876b6 8.0.0-20250905150616-ba86dfc5876b6

References

cvelogic Threat Intelligence