Skip to content
Noroxi
CVE-2026-6689· NVD / CVE Program· CNA Mattermost

*Missing* {{invite_user}} *permission check on team creation allows unprivileged users to set open-invite and allowed-domains team settings*

Mattermost versions 11.6.x <= 11.6.1, 11.5.x <= 11.5.4, 10.11.x <= 10.11.15, 10.11.x <= 10.11.16 Fail to enforce PermissionInviteUser when setting AllowOpenInvite or AllowedDomains during team creation (the check was only applied on update/patch), which allows an authenticated user holding PermissionCreateTeam but not PermissionInviteUser on the resulting team to configure invite-controlled team settings (make the team publicly joinable via open invite and/or constrain membership via allowed domains) that they are not permitted to set on an existing team via POST /api/v4/teams with allow_open_invite: true and/or a non-empty allowed_domains in the request body.. Mattermost Advisory ID: MMSA-2026-00655

MediumCVSS 4.3 · v3.1—No exploit Fix available
Published
Jun 12, 2026
Updated
Jun 18, 2026
EPSS
0.3% · 16th percentile
Follow this CVE

Sign in to follow · You’ll be notified if a followed record enters KEV, gets an exploit or is updated.

Report tools

JSON

Action score

17

Monitor

Low priority for now.

CVSS
17 / 40 · 4.3 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.3%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · Mattermost
4.3
NVD has not scored this yet; the score shown is the CNA’s.

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Noroxi analysis

No Noroxi analysis for this record yet

We don't hand-write analysis for the hundreds of thousands of vulnerabilities in the database; that wouldn't be honest. For notable, high-impact vulnerabilities our team writes the mechanism, detection and remediation steps.

We use this product, ask for help

Affected systems

VendorProduct
mattermostmattermost server

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • mattermost mattermost server10.11.0 and later · before 10.11.17
  • mattermost mattermost server11.5.0 and later · before 11.5.5
  • mattermost mattermost server11.6.0 and later · before 11.6.2

Versions reported by the vendor

Affected version ranges reported by the assigning authority (Mattermost). Independent of NVD's CPE analysis and usually ahead of it.

  • Mattermost Mattermost

    • 11.7.0, 11.6.2, 11.5.5, 10.11.16, 10.11.17not affected
    • 11.6.0 and later · up to and including 11.6.1affected · semver
    • 11.5.0 and later · up to and including 11.5.4affected · semver
    • 10.11.0 and later · up to and including 10.11.15affected · semver
    • 10.11.0 and later · up to and including 10.11.16affected · semver

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Gogithub.com/mattermost/mattermost-serverfrom 10.11.0 · before 10.11.1710.11.17
Gogithub.com/mattermost/mattermost-serverfrom 10.11.0+incompatible · before 10.11.17+incompatible10.11.17+incompatible
Gogithub.com/mattermost/mattermost-serverfrom 11.5.0 · before 11.5.511.5.5
Gogithub.com/mattermost/mattermost-serverfrom 11.5.0+incompatible · before 11.5.5+incompatible11.5.5+incompatible
Gogithub.com/mattermost/mattermost-serverfrom 11.6.0 · before 11.6.111.6.1
Gogithub.com/mattermost/mattermost-serverfrom 11.6.0+incompatible · before 11.6.1+incompatible11.6.1+incompatible
Gogithub.com/mattermost/mattermost-server/v5all versions—
Gogithub.com/mattermost/mattermost-server/v6all versions—
Gogithub.com/mattermost/mattermost/server/v8from 8.0.0-20250731163400-5b955468ea1e · before 8.0.0-20260501144115-7d6816abdfd18.0.0-20260501144115-7d6816abdfd1

Same product

mattermost: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-4858Path traversal in integration action URL leading to arbitrary API execution via system admin’s auth token.
    39Monitor
  • CVE-2025-12421Account Takeover via Code Exchange Endpoint
    39Monitor
  • CVE-2025-12419Account takeover on OAuth/OpenID-enabled servers
    39Monitor
  • CVE-2025-4981Path Traversal Leading to RCE by Any Authenticated Mattermost User
    39Monitor
  • CVE-2023-6458Client side path traversal due to lack of route parameters validation
    39Monitor
  • CVE-2017-18920An issue was discovered in Mattermost Server before 3.6.2.
    39Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Go:github.com/mattermost/mattermost-server10.11.17Package registry (OSV)
Go:github.com/mattermost/mattermost-server10.11.17+incompatiblePackage registry (OSV)
Go:github.com/mattermost/mattermost-server11.5.5Package registry (OSV)
Go:github.com/mattermost/mattermost-server11.5.5+incompatiblePackage registry (OSV)
Go:github.com/mattermost/mattermost-server11.6.1Package registry (OSV)
Go:github.com/mattermost/mattermost-server11.6.1+incompatiblePackage registry (OSV)
Go:github.com/mattermost/mattermost/server/v88.0.0-20260501144115-7d6816abdfd1Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

  • CVE-2025-58073239 days apartArbitrary Mattermost Team can be joined by manipulating the OAuth state
    32Monitor
  • CVE-2025-58075239 days apartArbitrary Mattermost Team can be joined by manipulating the SAML RelayState
    32Monitor
  • CVE-2026-882194 days apartPlaybooks run owner channel membership permission bypass
    28Monitor
  • CVE-2026-311725 days apartInstance and webhook GitLab plugin commands were able to be run by non-admin users
    26Monitor
  • CVE-2026-516325 days apartMissing authorization check in AI message rewrite endpoint allows access to private thread content
    26Monitor
  • CVE-2025-9076270 days apartMattermost Server exposes sensitive user credentials during shared channel membership synchronization
    26Monitor

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

The product’s vendor appears in a public program. Matched by name; verify the scope text in the program.

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • A low-privileged account is enough.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
none
Integrity
low · data or configuration can be modified
Availability
none
Attack vector
Network
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality impact
None
Integrity impact
Low
Availability impact
None

Weakness class (CWE)

CWE-862 · Missing Authorization

CVSS vector

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

nvd-secondary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records