Is CVE-2026-6343 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-6343 being exploited in the wild.

How severe is CVE-2026-6343?

Medium severity, with a CVSS score of 4.3, published 18 May 2026.

Which products and versions are affected?

github.com/mattermost/mattermost-plugin-playbooks (Go) SEMVER:introduced=0,fixed=1.41.1-0.20260309184833-887d9cacb616; github.com/mattermost/mattermost-server (Go) SEMVER:introduced=10.11.0+incompatible,fixed=10.11.14+incompatible,introduced=11.4.0+incompatible,fixed=11.4.4+incompatible,introduced=11.5.0+incompatible,fixed=11.5.2+incompatible; github.com/mattermost/mattermost-server/v5 (Go) SEMVER:introduced=0; github.com/mattermost/mattermost-server/v6 (Go) SEMVER:introduced=0; and 3 more.

Is there a fix for CVE-2026-6343?

Yes. github.com/mattermost/mattermost-plugin-playbooks (Go): upgrade to 1.41.1-0.20260309184833-887d9cacb616 or later; github.com/mattermost/mattermost-server (Go): upgrade to 11.5.2+incompatible or later; github.com/mattermost/mattermost/server/v8 (Go): upgrade to 11.5.2 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

How is CVE-2026-6343 attacked?

It is attacked over the network, in a network appliance.

Am I affected by CVE-2026-6343?

Check whether you run github.com/mattermost/mattermost-plugin-playbooks (Go), github.com/mattermost/mattermost-server (Go), github.com/mattermost/mattermost-server/v5 (Go) or one of the others listed at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-6343: Mattermost Incorrect Authorization in Playbooks via /get endpoint

CVE-2026-6343 · Severity: medium · CVSS 4.3 · Published 2026-05-18

Mattermost, a collaboration and incident response platform, contains a flaw in how it handles permissions for its Playbooks feature. This vulnerability allows users who do not have the appropriate authorization to view public playbooks that should otherwise be restricted. While this does not allow for data modification, it could lead to the unauthorized disclosure of internal workflows and operational procedures.

Technologies: github.com/mattermost/mattermost-plugin-playbooks (Go), github.com/mattermost/mattermost-server (Go), github.com/mattermost/mattermost-server/v5 (Go), github.com/mattermost/mattermost-server/v6 (Go), github.com/mattermost/mattermost/server/v8 (Go), Mattermost Server. Vendors: Go, Mattermost.

Quick answers

Is CVE-2026-6343 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-6343 being exploited in the wild.
How severe is CVE-2026-6343?: Medium severity, with a CVSS score of 4.3, published 18 May 2026.
Which products and versions are affected?: github.com/mattermost/mattermost-plugin-playbooks (Go) SEMVER:introduced=0,fixed=1.41.1-0.20260309184833-887d9cacb616; github.com/mattermost/mattermost-server (Go) SEMVER:introduced=10.11.0+incompatible,fixed=10.11.14+incompatible,introduced=11.4.0+incompatible,fixed=11.4.4+incompatible,introduced=11.5.0+incompatible,fixed=11.5.2+incompatible; github.com/mattermost/mattermost-server/v5 (Go) SEMVER:introduced=0; github.com/mattermost/mattermost-server/v6 (Go) SEMVER:introduced=0; and 3 more.
Is there a fix for CVE-2026-6343?: Yes. github.com/mattermost/mattermost-plugin-playbooks (Go): upgrade to 1.41.1-0.20260309184833-887d9cacb616 or later; github.com/mattermost/mattermost-server (Go): upgrade to 11.5.2+incompatible or later; github.com/mattermost/mattermost/server/v8 (Go): upgrade to 11.5.2 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-6343 attacked?: It is attacked over the network, in a network appliance.
Am I affected by CVE-2026-6343?: Check whether you run github.com/mattermost/mattermost-plugin-playbooks (Go), github.com/mattermost/mattermost-server (Go), github.com/mattermost/mattermost-server/v5 (Go) or one of the others listed at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

github.com/mattermost/mattermost-plugin-playbooks (Go): upgrade to 1.41.1-0.20260309184833-887d9cacb616 or later
```
go get github.com/mattermost/mattermost-plugin-playbooks@v1.41.1-0.20260309184833-887d9cacb616
```
github.com/mattermost/mattermost-server (Go): upgrade to 11.5.2+incompatible or later
```
go get github.com/mattermost/mattermost-server@v11.5.2+incompatible
```
github.com/mattermost/mattermost/server/v8 (Go): upgrade to 11.5.2 or later
```
go get github.com/mattermost/mattermost/server/v8@v11.5.2
```

Technical details

An incorrect authorization vulnerability (CWE-863) exists in Mattermost Server and the Playbooks plugin. The application fails to perform adequate permission checks when a user attempts to access public playbooks via the '/get' endpoint. An authenticated attacker with low privileges can bypass intended access controls to retrieve playbook data they are not authorized to see. The issue is rooted in the Playbooks plugin's handling of category and permission services. Patches have been released in Mattermost Server versions 11.5.2, 11.4.4, and 10.11.14, as well as Playbooks plugin version 1.41.1 (commit 887d9ca).

Affected products

Mattermost Mattermost Server 11.5.0 to 11.5.1, 11.4.0 to 11.4.3, 10.11.0 to 10.11.13
Mattermost Mattermost Playbooks Plugin < 1.41.1-0.20260309184833-887d9cacb616

Identifiers

CVE-2026-6343
GHSA-m79q-8qf5-v622
GO-2026-5494

Timeline

2026-03-09: patched: Fix committed to Playbooks plugin repository
2026-05-18: disclosed: NVD and GitHub Advisory published
2026-06-01: advisory: Advisory reviewed and updated

References

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