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884 vulnerabilities found for Mattermost by Mattermost
CVE-2026-9693 (GCVE-0-2026-9693)
Vulnerability from nvd – Published: 2026-08-17 22:07 – Updated: 2026-08-18 14:21
VLAI
EPSS
VEX
Title
Mattermost thread memberships persist after team removal, exposing private channel thread metadata on re-invite
Summary
Mattermost versions 10.11.x <= 10.11.20, 11.7.x <= 11.7.5 Mattermost fails to remove thread membership records when a user is removed from or leaves a team, which allows a previously removed user who is later re-invited to the team to view private channel thread root post content and metadata via the team threads API.. Mattermost Advisory ID: MMSA-2026-00682
Severity
SSVC
Exploitation: none
Automatable: no
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-08-18 14:20 UTC
CWE
- CWE-459 - Incomplete Cleanup
Assigner
References
1 reference
| URL | Tags |
|---|---|
| https://mattermost.com/security-updates | vendor-advisory |
Impacted products
1 product
| Vendor | Product | Version | |
|---|---|---|---|
| Mattermost | Mattermost |
Affected:
10.11.0 , ≤ 10.11.20
(semver)
Affected: 11.7.0 , ≤ 11.7.5 (semver) Unaffected: 11.9.0 Unaffected: 10.11.21 Unaffected: 11.7.6 |
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CVE-2026-75587 (GCVE-0-2026-75587)
Vulnerability from nvd – Published: 2026-08-17 22:09 – Updated: 2026-08-18 14:20
VLAI
EPSS
VEX
Title
Plaintext pre-auth secret exposure via Desktop App diagnostics report
Summary
Mattermost Desktop App versions <=6.2 6.2.2.0 fail to redact the pre-auth secret when generating a diagnostics report, which allows a local attacker with access to a user's diagnostics report or log files to obtain the plaintext pre-auth secret configured for a connected server via inspecting the Server Connectivity (Step-3) diagnostics output. Mattermost Advisory ID: MMSA-2026-00716
Severity
SSVC
Exploitation: none
Automatable: no
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-08-18 14:19 UTC
CWE
- CWE-200 - Exposure of Sensitive Information to an Unauthorized Actor
Assigner
References
1 reference
| URL | Tags |
|---|---|
| https://mattermost.com/security-updates | vendor-advisory |
Impacted products
1 product
| Vendor | Product | Version | |
|---|---|---|---|
| Mattermost | Mattermost |
Affected:
0 , ≤ 6.2.2
(semver)
Unaffected: 6.3.0 Unaffected: 6.2.3.0 |
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CVE-2026-9859 (GCVE-0-2026-9859)
Vulnerability from nvd – Published: 2026-08-17 22:06 – Updated: 2026-08-18 14:22
VLAI
EPSS
VEX
Title
Mattermost Boards plugin didn’t enforce role-based authorization on board channel link allowing board editors to expose boards to arbitrary channels
Summary
Mattermost versions 11.7.x <= 11.7.6, 10.11.x <= 10.11.21, 11.8.x <= 11.8.3 fail to enforce PermissionManageBoardRoles on the channelId field of the batch endpoint, which allows an authenticated board editor to relink any board they can edit to an arbitrary channel via a crafted PATCH request. Mattermost Advisory ID: MMSA-2026-00686
Severity
6.5 (Medium)
SSVC
Exploitation: none
Automatable: no
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-08-18 14:21 UTC
CWE
- CWE-863 - Incorrect Authorization
Assigner
References
1 reference
| URL | Tags |
|---|---|
| https://mattermost.com/security-updates | vendor-advisory |
Impacted products
1 product
| Vendor | Product | Version | |
|---|---|---|---|
| Mattermost | Mattermost |
Affected:
11.7.0 , ≤ 11.7.6
(semver)
Affected: 10.11.0 , ≤ 10.11.21 (semver) Affected: 11.8.0 , ≤ 11.8.3 (semver) Unaffected: 11.9.0 Unaffected: 11.7.7 Unaffected: 10.11.22 Unaffected: 11.8.4 |
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CVE-2026-9816 (GCVE-0-2026-9816)
Vulnerability from nvd – Published: 2026-08-17 22:05 – Updated: 2026-08-18 15:26
VLAI
EPSS
VEX
Title
Insufficient server-side validation of board member role fields permits privilege escalation
Summary
Mattermost versions 11.7.x <= 11.7.6, 10.11.x <= 10.11.21, 11.8.x <= 11.8.3 fail to validate BoardMember.Scheme* fields server-side on insert and archive-import paths which allows a board editor or non-guest team member to grant board admin to arbitrary users via POST /api/v2/boards/{boardID}/members and POST /api/v2/teams/{teamID}/archive/import.. Mattermost Advisory ID: MMSA-2026-00685
Severity
8.3 (High)
SSVC
Exploitation: none
Automatable: no
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-08-18 15:23 UTC
CWE
- CWE-863 - Incorrect Authorization
Assigner
References
1 reference
| URL | Tags |
|---|---|
| https://mattermost.com/security-updates | vendor-advisory |
Impacted products
1 product
| Vendor | Product | Version | |
|---|---|---|---|
| Mattermost | Mattermost |
Affected:
11.7.0 , ≤ 11.7.6
(semver)
Affected: 10.11.0 , ≤ 10.11.21 (semver) Affected: 11.8.0 , ≤ 11.8.3 (semver) Unaffected: 11.9.0 Unaffected: 11.7.7 Unaffected: 10.11.22 Unaffected: 11.8.4 |
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CVE-2026-10080 (GCVE-0-2026-10080)
Vulnerability from nvd – Published: 2026-08-17 22:04 – Updated: 2026-08-18 15:23
VLAI
EPSS
VEX
Title
Boards plugin panics on WebSocket command with non-string field types
Summary
Mattermost versions 11.7.x <= 11.7.6, 10.11.x <= 10.11.21, 11.8.x <= 11.8.3 fails to validate WebSocket command field types which allows an authenticated user to crash the plugin process and deny service to all Boards users via a custom_focalboard_SUBSCRIBE_TEAM message with a non-string teamId.. Mattermost Advisory ID: MMSA-2026-00687
Severity
6.5 (Medium)
SSVC
Exploitation: none
Automatable: no
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-08-18 15:23 UTC
CWE
- CWE-704 - Incorrect Type Conversion or Cast
Assigner
References
1 reference
| URL | Tags |
|---|---|
| https://mattermost.com/security-updates | vendor-advisory |
Impacted products
1 product
| Vendor | Product | Version | |
|---|---|---|---|
| Mattermost | Mattermost |
Affected:
11.7.0 , ≤ 11.7.6
(semver)
Affected: 10.11.0 , ≤ 10.11.21 (semver) Affected: 11.8.0 , ≤ 11.8.3 (semver) Unaffected: 11.9.0 Unaffected: 11.7.7 Unaffected: 10.11.22 Unaffected: 11.8.4 |
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CVE-2026-16049 (GCVE-0-2026-16049)
Vulnerability from nvd – Published: 2026-08-17 14:25 – Updated: 2026-08-17 15:26
VLAI
EPSS
VEX
Title
_GitLab Plugin allows cross-channel post injection and phishing via missing channel permission checks in issue API endpoints_
Summary
Mattermost Plugins versions <=11.8 10.20.11 11.5.7.0 _The Mattermost GitLab plugin fails to verify channel permissions when processing API requests with a caller-supplied_ {{post_id}}_, and fails to validate the_ {{web_url}} _parameter against the configured GitLab instance, which allows an authenticated attacker to inject bot-authored messages containing arbitrary URLs into channels they do not have access to via the_ {{createIssue}} _and_ {{attachCommentToIssue}} _API endpoints._ Mattermost Advisory ID: MMSA-2026-00673
Severity
SSVC
Exploitation: none
Automatable: no
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-08-17 14:51 UTC
CWE
- CWE-862 - Missing Authorization
Assigner
References
1 reference
| URL | Tags |
|---|---|
| https://mattermost.com/security-updates | vendor-advisory |
Impacted products
1 product
| Vendor | Product | Version | |
|---|---|---|---|
| Mattermost | Mattermost |
Affected:
0 , ≤ 10.20.11
(semver)
Affected: 0 , ≤ 11.5.7 (semver) Unaffected: 11.9.0 Unaffected: 10.11.21 Unaffected: 11.7.6 |
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CVE-2026-16048 (GCVE-0-2026-16048)
Vulnerability from nvd – Published: 2026-08-17 14:22 – Updated: 2026-08-17 15:37
VLAI
EPSS
VEX
Title
Channel member roles accept out-of-scope roles
Summary
Mattermost versions 11.8.x <= 11.8.2, 11.7.x <= 11.7.6, 10.11.x <= 10.11.21 fail to restrict channel member role assignment to channel-scoped roles which allows a channel administrator to gain additional channel permissions via the channel member roles API.. Mattermost Advisory ID: MMSA-2026-00697
Severity
6.3 (Medium)
SSVC
Exploitation: none
Automatable: no
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-08-17 14:51 UTC
CWE
- CWE-863 - Incorrect Authorization
Assigner
References
1 reference
| URL | Tags |
|---|---|
| https://mattermost.com/security-updates | vendor-advisory |
Impacted products
1 product
| Vendor | Product | Version | |
|---|---|---|---|
| Mattermost | Mattermost |
Affected:
11.8.0 , ≤ 11.8.2
(semver)
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CVE-2026-16047 (GCVE-0-2026-16047)
Vulnerability from nvd – Published: 2026-08-17 14:25 – Updated: 2026-08-17 15:26
VLAI
EPSS
VEX
Title
Board channel linking without read channel permission validation
Summary
Mattermost versions 11.7.x <= 11.7.6, 10.11.x <= 10.11.21, 11.8.x <= 11.8.3 fail to validate that users have read access to a channel before linking a board to it, which allows an authenticated attacker to discover the membership of private channels on the same team via creating, patching, importing, or bulk-creating boards with an arbitrary channelId. Mattermost Advisory ID: MMSA-2026-00674
Severity
4.3 (Medium)
SSVC
Exploitation: none
Automatable: no
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-08-17 14:51 UTC
CWE
- CWE-862 - Missing Authorization
Assigner
References
1 reference
| URL | Tags |
|---|---|
| https://mattermost.com/security-updates | vendor-advisory |
Impacted products
1 product
| Vendor | Product | Version | |
|---|---|---|---|
| Mattermost | Mattermost |
Affected:
11.7.0 , ≤ 11.7.6
(semver)
Affected: 10.11.0 , ≤ 10.11.21 (semver) Affected: 11.8.0 , ≤ 11.8.3 (semver) Unaffected: 11.9.0 Unaffected: 11.7.7 Unaffected: 10.11.22 Unaffected: 11.8.4 |
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CVE-2026-16046 (GCVE-0-2026-16046)
Vulnerability from nvd – Published: 2026-08-17 14:24 – Updated: 2026-08-18 13:22
VLAI
EPSS
VEX
Title
Missing run-state validation on finished playbook runs
Summary
Mattermost versions 11.7.x <= 11.7.6, 10.11.x <= 10.11.21 fail to enforce run-state validation on write operations for finished playbook runs which allows a run participant to modify status, checklists, retrospective content, ownership, and participants on completed runs via REST and GraphQL API requests. Mattermost Advisory ID: MMSA-2026-00675
Severity
SSVC
Exploitation: none
Automatable: no
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-08-17 14:51 UTC
CWE
- CWE-863 - Incorrect Authorization
Assigner
References
1 reference
| URL | Tags |
|---|---|
| https://mattermost.com/security-updates | vendor-advisory |
Impacted products
1 product
| Vendor | Product | Version | |
|---|---|---|---|
| Mattermost | Mattermost |
Affected:
11.7.0 , ≤ 11.7.6
(semver)
Affected: 10.11.0 , ≤ 10.11.21 (semver) Unaffected: 11.9.0 Unaffected: 11.7.7 Unaffected: 10.11.22 |
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CVE-2026-16045 (GCVE-0-2026-16045)
Vulnerability from nvd – Published: 2026-08-17 14:26 – Updated: 2026-08-17 15:26
VLAI
EPSS
VEX
Title
Delegated OAuth tokens could revoke unrelated OAuth application authorizations
Summary
Mattermost versions 11.7.x <= 11.7.6, 10.11.x <= 10.11.21 Mattermost failed to restrict OAuth deauthorization and personal access token management endpoints to direct user sessions, which allowed an OAuth app with a delegated user token to revoke the user's authorizations or tokens for other integrations via account-management endpoints.. Mattermost Advisory ID: MMSA-2026-00704
Severity
SSVC
Exploitation: none
Automatable: no
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-08-17 14:50 UTC
CWE
- CWE-863 - Incorrect Authorization
Assigner
References
1 reference
| URL | Tags |
|---|---|
| https://mattermost.com/security-updates | vendor-advisory |
Impacted products
1 product
| Vendor | Product | Version | |
|---|---|---|---|
| Mattermost | Mattermost |
Affected:
11.7.0 , ≤ 11.7.6
(semver)
Affected: 10.11.0 , ≤ 10.11.21 (semver) Unaffected: 11.9.0 Unaffected: 11.7.7 Unaffected: 10.11.22 |
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CVE-2026-16044 (GCVE-0-2026-16044)
Vulnerability from nvd – Published: 2026-08-17 14:26 – Updated: 2026-08-17 15:25
VLAI
EPSS
VEX
Title
Insufficient validation of guest board admin privileges on archive import
Summary
Mattermost versions 11.7.x <= 11.7.6, 10.11.x <= 10.11.21 fail to prevent guest users from receiving Board Admin privileges during board archive import which allows a board member to escalate a guest user to Board Admin via importing a crafted .boardarchive file. Mattermost Advisory ID: MMSA-2026-00672
Severity
SSVC
Exploitation: none
Automatable: no
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-08-17 14:50 UTC
CWE
- CWE-863 - Incorrect Authorization
Assigner
References
1 reference
| URL | Tags |
|---|---|
| https://mattermost.com/security-updates | vendor-advisory |
Impacted products
1 product
| Vendor | Product | Version | |
|---|---|---|---|
| Mattermost | Mattermost |
Affected:
11.7.0 , ≤ 11.7.6
(semver)
Affected: 10.11.0 , ≤ 10.11.21 (semver) Unaffected: 11.9.0 Unaffected: 11.7.7 Unaffected: 10.11.22 |
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CVE-2026-15754 (GCVE-0-2026-15754)
Vulnerability from nvd – Published: 2026-08-17 14:36 – Updated: 2026-08-17 15:25
VLAI
EPSS
VEX
Title
Missing per-channel team-scope check in ABAC access control policy unassign allows cross-team policy removal
Summary
Mattermost versions 11.7.x <= 11.7.6, 11.8.x <= 11.8.3 The access control policy unassign endpoint fails to re-validate that each target channel still belongs to the requesting admin's team, which allows an authenticated team administrator to remove ABAC (attribute-based access control) policy assignments from channels outside their team via the policy unassign API after a channel has been moved to another team.. Mattermost Advisory ID: MMSA-2026-00718
Severity
4.2 (Medium)
SSVC
Exploitation: none
Automatable: no
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-08-17 14:50 UTC
CWE
- CWE-863 - Incorrect Authorization
Assigner
References
1 reference
| URL | Tags |
|---|---|
| https://mattermost.com/security-updates | vendor-advisory |
Impacted products
1 product
| Vendor | Product | Version | |
|---|---|---|---|
| Mattermost | Mattermost |
Affected:
11.7.0 , ≤ 11.7.6
(semver)
Affected: 11.8.0 , ≤ 11.8.3 (semver) Unaffected: 11.9.0 Unaffected: 11.7.7 Unaffected: 11.8.4 |
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CVE-2026-10527 (GCVE-0-2026-10527)
Vulnerability from nvd – Published: 2026-08-17 14:37 – Updated: 2026-08-17 15:25
VLAI
EPSS
VEX
Title
Boards plugin retains Board Admin rights for users demoted to System Guest
Summary
Mattermost versions 11.7.x <= 11.7.6, 10.11.x <= 10.11.21, 11.8.x <= 11.8.3 fails to reconcile SchemeAdmin flags with a user's current role which allows a user demoted to System Guest to retain Board Admin privileges and perform admin-only operations via the Boards REST API or UI.. Mattermost Advisory ID: MMSA-2026-00691
Severity
6.3 (Medium)
SSVC
Exploitation: none
Automatable: no
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-08-17 14:50 UTC
CWE
- CWE-863 - Incorrect Authorization
Assigner
References
1 reference
| URL | Tags |
|---|---|
| https://mattermost.com/security-updates | vendor-advisory |
Impacted products
1 product
| Vendor | Product | Version | |
|---|---|---|---|
| Mattermost | Mattermost |
Affected:
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CVE-2026-14298 (GCVE-0-2026-14298)
Vulnerability from nvd – Published: 2026-08-13 08:03 – Updated: 2026-08-13 14:16
VLAI
EPSS
VEX
Title
Denial of service via resource exhaustion in Mattermost
Summary
Mattermost versions 11.9.x <= 11.9.0, 11.8.x <= 11.8.4, 11.7.x <= 11.7.7, 10.11.x <= 10.11.22 fail to properly limit resource consumption when processing certain user-supplied input, which allows an authenticated user to cause a denial of service. Mattermost Advisory ID: MMSA-2026-00713
Severity
6.5 (Medium)
SSVC
Exploitation: none
Automatable: no
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-08-13 14:16 UTC
CWE
- CWE-409 - Improper Handling of Highly Compressed Data (Data Amplification)
Assigner
References
1 reference
| URL | Tags |
|---|---|
| https://mattermost.com/security-updates | vendor-advisory |
Impacted products
1 product
| Vendor | Product | Version | |
|---|---|---|---|
| Mattermost | Mattermost |
Affected:
11.9.0 , ≤ 11.9.0
(semver)
Affected: 11.8.0 , ≤ 11.8.4 (semver) Affected: 11.7.0 , ≤ 11.7.7 (semver) Affected: 10.11.0 , ≤ 10.11.22 (semver) Unaffected: 11.10.0 Unaffected: 11.9.1 Unaffected: 11.8.5 Unaffected: 11.7.8 Unaffected: 10.11.23 |
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CVE-2026-7521 (GCVE-0-2026-7521)
Vulnerability from nvd – Published: 2026-07-28 13:58 – Updated: 2026-07-28 14:48
VLAI
EPSS
VEX
Title
SAML certificate deletion allows path traversal to delete arbitrary files outside the config directory
Summary
Mattermost versions 11.8.x <= 11.8.0, 11.7.x <= 11.7.3, 11.6.x <= 11.6.5, 10.11.x <= 10.11.20 fail to verify file deletion path which allows an admin with SAML system-console write permissions to delete arbitrary files outside the config directory from the server via the remove file endpoint.. Mattermost Advisory ID: MMSA-2026-00666
Severity
5.5 (Medium)
SSVC
Exploitation: none
Automatable: no
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-07-28 14:47 UTC
CWE
- CWE-22 - Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
Assigner
References
1 reference
| URL | Tags |
|---|---|
| https://mattermost.com/security-updates | vendor-advisory |
Impacted products
1 product
| Vendor | Product | Version | |
|---|---|---|---|
| Mattermost | Mattermost |
Affected:
11.8.0 , ≤ 11.8.0
(semver)
Affected: 11.7.0 , ≤ 11.7.3 (semver) Affected: 11.6.0 , ≤ 11.6.5 (semver) Affected: 10.11.0 , ≤ 10.11.20 (semver) Unaffected: 11.9.0 Unaffected: 11.8.1 Unaffected: 11.7.4 Unaffected: 11.6.6 Unaffected: 10.11.21 |
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CVE-2026-75587 (GCVE-0-2026-75587)
Vulnerability from cvelistv5 – Published: 2026-08-17 22:09 – Updated: 2026-08-18 14:20
VLAI
EPSS
VEX
Title
Plaintext pre-auth secret exposure via Desktop App diagnostics report
Summary
Mattermost Desktop App versions <=6.2 6.2.2.0 fail to redact the pre-auth secret when generating a diagnostics report, which allows a local attacker with access to a user's diagnostics report or log files to obtain the plaintext pre-auth secret configured for a connected server via inspecting the Server Connectivity (Step-3) diagnostics output. Mattermost Advisory ID: MMSA-2026-00716
Severity
SSVC
Exploitation: none
Automatable: no
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-08-18 14:19 UTC
CWE
- CWE-200 - Exposure of Sensitive Information to an Unauthorized Actor
Assigner
References
1 reference
| URL | Tags |
|---|---|
| https://mattermost.com/security-updates | vendor-advisory |
Impacted products
1 product
| Vendor | Product | Version | |
|---|---|---|---|
| Mattermost | Mattermost |
Affected:
0 , ≤ 6.2.2
(semver)
Unaffected: 6.3.0 Unaffected: 6.2.3.0 |
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CVE-2026-9693 (GCVE-0-2026-9693)
Vulnerability from cvelistv5 – Published: 2026-08-17 22:07 – Updated: 2026-08-18 14:21
VLAI
EPSS
VEX
Title
Mattermost thread memberships persist after team removal, exposing private channel thread metadata on re-invite
Summary
Mattermost versions 10.11.x <= 10.11.20, 11.7.x <= 11.7.5 Mattermost fails to remove thread membership records when a user is removed from or leaves a team, which allows a previously removed user who is later re-invited to the team to view private channel thread root post content and metadata via the team threads API.. Mattermost Advisory ID: MMSA-2026-00682
Severity
SSVC
Exploitation: none
Automatable: no
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-08-18 14:20 UTC
CWE
- CWE-459 - Incomplete Cleanup
Assigner
References
1 reference
| URL | Tags |
|---|---|
| https://mattermost.com/security-updates | vendor-advisory |
Impacted products
1 product
| Vendor | Product | Version | |
|---|---|---|---|
| Mattermost | Mattermost |
Affected:
10.11.0 , ≤ 10.11.20
(semver)
Affected: 11.7.0 , ≤ 11.7.5 (semver) Unaffected: 11.9.0 Unaffected: 10.11.21 Unaffected: 11.7.6 |
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CVE-2026-9859 (GCVE-0-2026-9859)
Vulnerability from cvelistv5 – Published: 2026-08-17 22:06 – Updated: 2026-08-18 14:22
VLAI
EPSS
VEX
Title
Mattermost Boards plugin didn’t enforce role-based authorization on board channel link allowing board editors to expose boards to arbitrary channels
Summary
Mattermost versions 11.7.x <= 11.7.6, 10.11.x <= 10.11.21, 11.8.x <= 11.8.3 fail to enforce PermissionManageBoardRoles on the channelId field of the batch endpoint, which allows an authenticated board editor to relink any board they can edit to an arbitrary channel via a crafted PATCH request. Mattermost Advisory ID: MMSA-2026-00686
Severity
6.5 (Medium)
SSVC
Exploitation: none
Automatable: no
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-08-18 14:21 UTC
CWE
- CWE-863 - Incorrect Authorization
Assigner
References
1 reference
| URL | Tags |
|---|---|
| https://mattermost.com/security-updates | vendor-advisory |
Impacted products
1 product
| Vendor | Product | Version | |
|---|---|---|---|
| Mattermost | Mattermost |
Affected:
11.7.0 , ≤ 11.7.6
(semver)
Affected: 10.11.0 , ≤ 10.11.21 (semver) Affected: 11.8.0 , ≤ 11.8.3 (semver) Unaffected: 11.9.0 Unaffected: 11.7.7 Unaffected: 10.11.22 Unaffected: 11.8.4 |
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CVE-2026-9816 (GCVE-0-2026-9816)
Vulnerability from cvelistv5 – Published: 2026-08-17 22:05 – Updated: 2026-08-18 15:26
VLAI
EPSS
VEX
Title
Insufficient server-side validation of board member role fields permits privilege escalation
Summary
Mattermost versions 11.7.x <= 11.7.6, 10.11.x <= 10.11.21, 11.8.x <= 11.8.3 fail to validate BoardMember.Scheme* fields server-side on insert and archive-import paths which allows a board editor or non-guest team member to grant board admin to arbitrary users via POST /api/v2/boards/{boardID}/members and POST /api/v2/teams/{teamID}/archive/import.. Mattermost Advisory ID: MMSA-2026-00685
Severity
8.3 (High)
SSVC
Exploitation: none
Automatable: no
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-08-18 15:23 UTC
CWE
- CWE-863 - Incorrect Authorization
Assigner
References
1 reference
| URL | Tags |
|---|---|
| https://mattermost.com/security-updates | vendor-advisory |
Impacted products
1 product
| Vendor | Product | Version | |
|---|---|---|---|
| Mattermost | Mattermost |
Affected:
11.7.0 , ≤ 11.7.6
(semver)
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CVE-2026-10080 (GCVE-0-2026-10080)
Vulnerability from cvelistv5 – Published: 2026-08-17 22:04 – Updated: 2026-08-18 15:23
VLAI
EPSS
VEX
Title
Boards plugin panics on WebSocket command with non-string field types
Summary
Mattermost versions 11.7.x <= 11.7.6, 10.11.x <= 10.11.21, 11.8.x <= 11.8.3 fails to validate WebSocket command field types which allows an authenticated user to crash the plugin process and deny service to all Boards users via a custom_focalboard_SUBSCRIBE_TEAM message with a non-string teamId.. Mattermost Advisory ID: MMSA-2026-00687
Severity
6.5 (Medium)
SSVC
Exploitation: none
Automatable: no
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-08-18 15:23 UTC
CWE
- CWE-704 - Incorrect Type Conversion or Cast
Assigner
References
1 reference
| URL | Tags |
|---|---|
| https://mattermost.com/security-updates | vendor-advisory |
Impacted products
1 product
| Vendor | Product | Version | |
|---|---|---|---|
| Mattermost | Mattermost |
Affected:
11.7.0 , ≤ 11.7.6
(semver)
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CVE-2026-10527 (GCVE-0-2026-10527)
Vulnerability from cvelistv5 – Published: 2026-08-17 14:37 – Updated: 2026-08-17 15:25
VLAI
EPSS
VEX
Title
Boards plugin retains Board Admin rights for users demoted to System Guest
Summary
Mattermost versions 11.7.x <= 11.7.6, 10.11.x <= 10.11.21, 11.8.x <= 11.8.3 fails to reconcile SchemeAdmin flags with a user's current role which allows a user demoted to System Guest to retain Board Admin privileges and perform admin-only operations via the Boards REST API or UI.. Mattermost Advisory ID: MMSA-2026-00691
Severity
6.3 (Medium)
SSVC
Exploitation: none
Automatable: no
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-08-17 14:50 UTC
CWE
- CWE-863 - Incorrect Authorization
Assigner
References
1 reference
| URL | Tags |
|---|---|
| https://mattermost.com/security-updates | vendor-advisory |
Impacted products
1 product
| Vendor | Product | Version | |
|---|---|---|---|
| Mattermost | Mattermost |
Affected:
11.7.0 , ≤ 11.7.6
(semver)
Affected: 10.11.0 , ≤ 10.11.21 (semver) Affected: 11.8.0 , ≤ 11.8.3 (semver) Unaffected: 11.9.0 Unaffected: 11.7.7 Unaffected: 10.11.22 Unaffected: 11.8.4 |
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CVE-2026-15754 (GCVE-0-2026-15754)
Vulnerability from cvelistv5 – Published: 2026-08-17 14:36 – Updated: 2026-08-17 15:25
VLAI
EPSS
VEX
Title
Missing per-channel team-scope check in ABAC access control policy unassign allows cross-team policy removal
Summary
Mattermost versions 11.7.x <= 11.7.6, 11.8.x <= 11.8.3 The access control policy unassign endpoint fails to re-validate that each target channel still belongs to the requesting admin's team, which allows an authenticated team administrator to remove ABAC (attribute-based access control) policy assignments from channels outside their team via the policy unassign API after a channel has been moved to another team.. Mattermost Advisory ID: MMSA-2026-00718
Severity
4.2 (Medium)
SSVC
Exploitation: none
Automatable: no
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-08-17 14:50 UTC
CWE
- CWE-863 - Incorrect Authorization
Assigner
References
1 reference
| URL | Tags |
|---|---|
| https://mattermost.com/security-updates | vendor-advisory |
Impacted products
1 product
| Vendor | Product | Version | |
|---|---|---|---|
| Mattermost | Mattermost |
Affected:
11.7.0 , ≤ 11.7.6
(semver)
Affected: 11.8.0 , ≤ 11.8.3 (semver) Unaffected: 11.9.0 Unaffected: 11.7.7 Unaffected: 11.8.4 |
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CVE-2026-16044 (GCVE-0-2026-16044)
Vulnerability from cvelistv5 – Published: 2026-08-17 14:26 – Updated: 2026-08-17 15:25
VLAI
EPSS
VEX
Title
Insufficient validation of guest board admin privileges on archive import
Summary
Mattermost versions 11.7.x <= 11.7.6, 10.11.x <= 10.11.21 fail to prevent guest users from receiving Board Admin privileges during board archive import which allows a board member to escalate a guest user to Board Admin via importing a crafted .boardarchive file. Mattermost Advisory ID: MMSA-2026-00672
Severity
SSVC
Exploitation: none
Automatable: no
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-08-17 14:50 UTC
CWE
- CWE-863 - Incorrect Authorization
Assigner
References
1 reference
| URL | Tags |
|---|---|
| https://mattermost.com/security-updates | vendor-advisory |
Impacted products
1 product
| Vendor | Product | Version | |
|---|---|---|---|
| Mattermost | Mattermost |
Affected:
11.7.0 , ≤ 11.7.6
(semver)
Affected: 10.11.0 , ≤ 10.11.21 (semver) Unaffected: 11.9.0 Unaffected: 11.7.7 Unaffected: 10.11.22 |
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CVE-2026-16045 (GCVE-0-2026-16045)
Vulnerability from cvelistv5 – Published: 2026-08-17 14:26 – Updated: 2026-08-17 15:26
VLAI
EPSS
VEX
Title
Delegated OAuth tokens could revoke unrelated OAuth application authorizations
Summary
Mattermost versions 11.7.x <= 11.7.6, 10.11.x <= 10.11.21 Mattermost failed to restrict OAuth deauthorization and personal access token management endpoints to direct user sessions, which allowed an OAuth app with a delegated user token to revoke the user's authorizations or tokens for other integrations via account-management endpoints.. Mattermost Advisory ID: MMSA-2026-00704
Severity
SSVC
Exploitation: none
Automatable: no
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-08-17 14:50 UTC
CWE
- CWE-863 - Incorrect Authorization
Assigner
References
1 reference
| URL | Tags |
|---|---|
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Impacted products
1 product
| Vendor | Product | Version | |
|---|---|---|---|
| Mattermost | Mattermost |
Affected:
11.7.0 , ≤ 11.7.6
(semver)
Affected: 10.11.0 , ≤ 10.11.21 (semver) Unaffected: 11.9.0 Unaffected: 11.7.7 Unaffected: 10.11.22 |
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CVE-2026-16049 (GCVE-0-2026-16049)
Vulnerability from cvelistv5 – Published: 2026-08-17 14:25 – Updated: 2026-08-17 15:26
VLAI
EPSS
VEX
Title
_GitLab Plugin allows cross-channel post injection and phishing via missing channel permission checks in issue API endpoints_
Summary
Mattermost Plugins versions <=11.8 10.20.11 11.5.7.0 _The Mattermost GitLab plugin fails to verify channel permissions when processing API requests with a caller-supplied_ {{post_id}}_, and fails to validate the_ {{web_url}} _parameter against the configured GitLab instance, which allows an authenticated attacker to inject bot-authored messages containing arbitrary URLs into channels they do not have access to via the_ {{createIssue}} _and_ {{attachCommentToIssue}} _API endpoints._ Mattermost Advisory ID: MMSA-2026-00673
Severity
SSVC
Exploitation: none
Automatable: no
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-08-17 14:51 UTC
CWE
- CWE-862 - Missing Authorization
Assigner
References
1 reference
| URL | Tags |
|---|---|
| https://mattermost.com/security-updates | vendor-advisory |
Impacted products
1 product
| Vendor | Product | Version | |
|---|---|---|---|
| Mattermost | Mattermost |
Affected:
0 , ≤ 10.20.11
(semver)
Affected: 0 , ≤ 11.5.7 (semver) Unaffected: 11.9.0 Unaffected: 10.11.21 Unaffected: 11.7.6 |
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CVE-2026-16047 (GCVE-0-2026-16047)
Vulnerability from cvelistv5 – Published: 2026-08-17 14:25 – Updated: 2026-08-17 15:26
VLAI
EPSS
VEX
Title
Board channel linking without read channel permission validation
Summary
Mattermost versions 11.7.x <= 11.7.6, 10.11.x <= 10.11.21, 11.8.x <= 11.8.3 fail to validate that users have read access to a channel before linking a board to it, which allows an authenticated attacker to discover the membership of private channels on the same team via creating, patching, importing, or bulk-creating boards with an arbitrary channelId. Mattermost Advisory ID: MMSA-2026-00674
Severity
4.3 (Medium)
SSVC
Exploitation: none
Automatable: no
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-08-17 14:51 UTC
CWE
- CWE-862 - Missing Authorization
Assigner
References
1 reference
| URL | Tags |
|---|---|
| https://mattermost.com/security-updates | vendor-advisory |
Impacted products
1 product
| Vendor | Product | Version | |
|---|---|---|---|
| Mattermost | Mattermost |
Affected:
11.7.0 , ≤ 11.7.6
(semver)
Affected: 10.11.0 , ≤ 10.11.21 (semver) Affected: 11.8.0 , ≤ 11.8.3 (semver) Unaffected: 11.9.0 Unaffected: 11.7.7 Unaffected: 10.11.22 Unaffected: 11.8.4 |
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CVE-2026-16046 (GCVE-0-2026-16046)
Vulnerability from cvelistv5 – Published: 2026-08-17 14:24 – Updated: 2026-08-18 13:22
VLAI
EPSS
VEX
Title
Missing run-state validation on finished playbook runs
Summary
Mattermost versions 11.7.x <= 11.7.6, 10.11.x <= 10.11.21 fail to enforce run-state validation on write operations for finished playbook runs which allows a run participant to modify status, checklists, retrospective content, ownership, and participants on completed runs via REST and GraphQL API requests. Mattermost Advisory ID: MMSA-2026-00675
Severity
SSVC
Exploitation: none
Automatable: no
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-08-17 14:51 UTC
CWE
- CWE-863 - Incorrect Authorization
Assigner
References
1 reference
| URL | Tags |
|---|---|
| https://mattermost.com/security-updates | vendor-advisory |
Impacted products
1 product
| Vendor | Product | Version | |
|---|---|---|---|
| Mattermost | Mattermost |
Affected:
11.7.0 , ≤ 11.7.6
(semver)
Affected: 10.11.0 , ≤ 10.11.21 (semver) Unaffected: 11.9.0 Unaffected: 11.7.7 Unaffected: 10.11.22 |
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CVE-2026-16048 (GCVE-0-2026-16048)
Vulnerability from cvelistv5 – Published: 2026-08-17 14:22 – Updated: 2026-08-17 15:37
VLAI
EPSS
VEX
Title
Channel member roles accept out-of-scope roles
Summary
Mattermost versions 11.8.x <= 11.8.2, 11.7.x <= 11.7.6, 10.11.x <= 10.11.21 fail to restrict channel member role assignment to channel-scoped roles which allows a channel administrator to gain additional channel permissions via the channel member roles API.. Mattermost Advisory ID: MMSA-2026-00697
Severity
6.3 (Medium)
SSVC
Exploitation: none
Automatable: no
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-08-17 14:51 UTC
CWE
- CWE-863 - Incorrect Authorization
Assigner
References
1 reference
| URL | Tags |
|---|---|
| https://mattermost.com/security-updates | vendor-advisory |
Impacted products
1 product
| Vendor | Product | Version | |
|---|---|---|---|
| Mattermost | Mattermost |
Affected:
11.8.0 , ≤ 11.8.2
(semver)
Affected: 11.7.0 , ≤ 11.7.6 (semver) Affected: 10.11.0 , ≤ 10.11.21 (semver) Unaffected: 11.9.0 Unaffected: 11.8.3 Unaffected: 11.7.7 Unaffected: 10.11.22 |
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CVE-2026-14298 (GCVE-0-2026-14298)
Vulnerability from cvelistv5 – Published: 2026-08-13 08:03 – Updated: 2026-08-13 14:16
VLAI
EPSS
VEX
Title
Denial of service via resource exhaustion in Mattermost
Summary
Mattermost versions 11.9.x <= 11.9.0, 11.8.x <= 11.8.4, 11.7.x <= 11.7.7, 10.11.x <= 10.11.22 fail to properly limit resource consumption when processing certain user-supplied input, which allows an authenticated user to cause a denial of service. Mattermost Advisory ID: MMSA-2026-00713
Severity
6.5 (Medium)
SSVC
Exploitation: none
Automatable: no
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-08-13 14:16 UTC
CWE
- CWE-409 - Improper Handling of Highly Compressed Data (Data Amplification)
Assigner
References
1 reference
| URL | Tags |
|---|---|
| https://mattermost.com/security-updates | vendor-advisory |
Impacted products
1 product
| Vendor | Product | Version | |
|---|---|---|---|
| Mattermost | Mattermost |
Affected:
11.9.0 , ≤ 11.9.0
(semver)
Affected: 11.8.0 , ≤ 11.8.4 (semver) Affected: 11.7.0 , ≤ 11.7.7 (semver) Affected: 10.11.0 , ≤ 10.11.22 (semver) Unaffected: 11.10.0 Unaffected: 11.9.1 Unaffected: 11.8.5 Unaffected: 11.7.8 Unaffected: 10.11.23 |
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CVE-2026-7521 (GCVE-0-2026-7521)
Vulnerability from cvelistv5 – Published: 2026-07-28 13:58 – Updated: 2026-07-28 14:48
VLAI
EPSS
VEX
Title
SAML certificate deletion allows path traversal to delete arbitrary files outside the config directory
Summary
Mattermost versions 11.8.x <= 11.8.0, 11.7.x <= 11.7.3, 11.6.x <= 11.6.5, 10.11.x <= 10.11.20 fail to verify file deletion path which allows an admin with SAML system-console write permissions to delete arbitrary files outside the config directory from the server via the remove file endpoint.. Mattermost Advisory ID: MMSA-2026-00666
Severity
5.5 (Medium)
SSVC
Exploitation: none
Automatable: no
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-07-28 14:47 UTC
CWE
- CWE-22 - Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
Assigner
References
1 reference
| URL | Tags |
|---|---|
| https://mattermost.com/security-updates | vendor-advisory |
Impacted products
1 product
| Vendor | Product | Version | |
|---|---|---|---|
| Mattermost | Mattermost |
Affected:
11.8.0 , ≤ 11.8.0
(semver)
Affected: 11.7.0 , ≤ 11.7.3 (semver) Affected: 11.6.0 , ≤ 11.6.5 (semver) Affected: 10.11.0 , ≤ 10.11.20 (semver) Unaffected: 11.9.0 Unaffected: 11.8.1 Unaffected: 11.7.4 Unaffected: 11.6.6 Unaffected: 10.11.21 |
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