Mattermost Exposure of Sensitive Information to an Unauthorized Actor vulnerability

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

4.3 · CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N

EPSS

• CVE-2023-45223: 0.51% estimated exploitation activity in the next 30 days; percentile 43.26 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Mattermost fails to properly validate the "Show Full Name" option in a few endpoints in Mattermost Boards, allowing a member to get the full name of another user even if the Show Full Name option was disabled.

Published by the source

27 Nov 2023, 12:30 UTC

Last modified by the source

28 Nov 2023, 20:49 UTC

Source last checked

26 Oct 2026, 15:00 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-p5pr-vm3j-jxxf

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# Patch Next advisory brief: CVE-2023-45223

Advisory: Mattermost Exposure of Sensitive Information to an Unauthorized Actor vulnerability
IDs: CVE-2023-45223, GHSA-p5pr-vm3j-jxxf
Record: https://patchnext.com/advisories/cve-2023-45223 (revision 1, source checked 26 Oct 2026, 15:00 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 4.3)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/mattermost/mattermost/server/v8 8.1.4; github.com/mattermost/mattermost-server/v6 7.8.13. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/mattermost/mattermost/server/v8: affected < 8.1.4; fixed in 8.1.4
- Go github.com/mattermost/mattermost-server/v6: affected < 7.8.13; fixed in 7.8.13

## Suggested inspection (read-only)
- Go github.com/mattermost/mattermost/server/v8: check the installed version with your package manager.
- Go github.com/mattermost/mattermost-server/v6: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/mattermost/mattermost/server/v8, github.com/mattermost/mattermost-server/v6.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-p5pr-vm3j-jxxf (GitHub-reviewed advisory GHSA-p5pr-vm3j-jxxf lists affected ranges: Go github.com/mattermost/mattermost/server/v8 >=0 =0 <7.8.13)

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