Mattermost fails to properly authentication inviter's permissions to private channel

Exploitation

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

CVSS

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

EPSS

• CVE-2023-1774: 0.32% estimated exploitation activity in the next 30 days; percentile 24.73 (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.

When processing an email invite to a private channel on a team, Mattermost fails to validate the inviter's permission to that channel, allowing an attacker to invite themselves to a private channel. Issue Identifier: MMSA-2023-00137

Published by the source

31 Mar 2023, 12:30 UTC

Last modified by the source

15 Apr 2023, 05:07 UTC

Source last checked

26 Oct 2026, 14:58 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-9hj7-v56g-rhf6

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# Patch Next advisory brief: CVE-2023-1774

Advisory: Mattermost fails to properly authentication inviter's permissions to private channel
IDs: CVE-2023-1774, GHSA-9hj7-v56g-rhf6
Record: https://patchnext.com/advisories/cve-2023-1774 (revision 1, source checked 26 Oct 2026, 14:58 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.4)
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/v6 7.1.6; github.com/mattermost/mattermost-server 7.7.2, 7.1.6; github.com/mattermost/mattermost-server/v5 7.1.6. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/mattermost/mattermost-server/v6: affected >= 6.0.0, <= 6.7.2; fixed in 7.1.6
- Go github.com/mattermost/mattermost-server: affected >= 3.3.0, <= 4.10.10; >= 7.7.0, <= 7.7.1; >= 7.1.0, <= 7.1.5; fixed in 7.7.2, 7.1.6
- Go github.com/mattermost/mattermost-server/v5: affected >= 5.0.0, <= 5.39.3; fixed in 7.1.6

## Suggested inspection (read-only)
- Go github.com/mattermost/mattermost-server/v6: check the installed version with your package manager.
- Go github.com/mattermost/mattermost-server: check the installed version with your package manager.
- Go github.com/mattermost/mattermost-server/v5: 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/v6, github.com/mattermost/mattermost-server, github.com/mattermost/mattermost-server/v5.
- 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-9hj7-v56g-rhf6 (GitHub-reviewed advisory GHSA-9hj7-v56g-rhf6 lists affected ranges: Go github.com/mattermost/mattermost-server >=3.3.0 =7.7.0 =7.1.0 =5.0.0 =6.0.0 <=6.7.2)

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