Mattermost fails to scope role_updated websocket events to authorized team and channel members
Noroxi assessment
Priority: Monitor (action score 17/100)
- The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
- Probability of exploitation in the next 30 days: 0.30% (FIRST EPSS).
- 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.
- Fixed version: github.com/mattermost/mattermost-server (Go) 10.11.17, 10.11.17+incompatible, 11.5.5; github.com/mattermost/mattermost/server/v8 (Go) 8.0.0-20260504071740-9408b98025d7; govulncheck-vulndb (openSUSE:Leap 16.0) 0.0.20260827T195228-160000.1.1.
Low priority for now. Upgrade to github.com/mattermost/mattermost-server (Go) 10.11.17, 10.11.17+incompatible, 11.5.5; github.com/mattermost/mattermost/server/v8 (Go) 8.0.0-20260504071740-9408b98025d7; govulncheck-vulndb (openSUSE:Leap 16.0) 0.0.20260827T195228-160000.1.1 or later.
Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it
Primary sources: NVD · CVE.org · FIRST EPSS
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 restrict role_updated websocket event broadcasts to members of the affected team or channel which allows an authenticated attacker with guest-level access to observe permission scheme change notifications for private teams they are not a member of via the websocket connection.. Mattermost Advisory ID: MMSA-2026-00616
- Published
- Jun 12, 2026
- Updated
- Jun 18, 2026
- EPSS
- 0.3% · 21th percentile
- CWE
- CWE-200
Report tools
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.
Get told when this record changes
- Not in KEV: no record of exploitation in the wild
- No public exploit code on record
- A fix has been released
If any of these changes, we'll tell you in the daily email digest.
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Noroxi analysis
What does it mean in your environment?
The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.
We use this product, ask for helpAffected systems
Is your version affected?
Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.
| Vendor | Product | CPE |
|---|---|---|
| mattermost | mattermost server | cpe:2.3:a:mattermost:mattermost_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.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| Go | github.com/mattermost/mattermost-server | from 10.11.0 · before 10.11.17 | 10.11.17 |
| Go | github.com/mattermost/mattermost-server | from 10.11.0+incompatible · before 10.11.17+incompatible | 10.11.17+incompatible |
| Go | github.com/mattermost/mattermost-server | from 11.5.0 · before 11.5.5 | 11.5.5 |
| Go | github.com/mattermost/mattermost-server | from 11.5.0+incompatible · before 11.5.5+incompatible | 11.5.5+incompatible |
| Go | github.com/mattermost/mattermost-server | from 11.6.0 · before 11.6.1 | 11.6.1 |
| Go | github.com/mattermost/mattermost-server | from 11.6.0+incompatible · before 11.6.1+incompatible | 11.6.1+incompatible |
| Go | github.com/mattermost/mattermost-server/v5 | from 0 | — |
| Go | github.com/mattermost/mattermost-server/v6 | from 0 | — |
| Go | github.com/mattermost/mattermost/server/v8 | from 8.0.0-20250731163400-5b955468ea1e · before 8.0.0-20260504071740-9408b98025d7 | 8.0.0-20260504071740-9408b98025d7 |
| openSUSE:Leap 16.0 | govulncheck-vulndb | before 0.0.20260827T195228-160000.1.1 | 0.0.20260827T195228-160000.1.1 |
| SUSE:Linux Enterprise Server 16.0 | govulncheck-vulndb | before 0.0.20260827T195228-160000.1.1 | 0.0.20260827T195228-160000.1.1 |
Same product
mattermost: all recordsOther 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 Endpoint39Monitor
- CVE-2025-12419Account takeover on OAuth/OpenID-enabled servers39Monitor
Published before and after this one in the same product
- ← EarlierCVE-2026-28735May 22, 2026 · GitHub OAuth Scope Validation21Monitor
- ← EarlierCVE-2026-4915May 25, 2026 · Server panic via outgoing webhook responses26Monitor
- Later →CVE-2026-6046Jun 12, 2026 · Plugin bot username conflict allows user account to be used as bot identity in Mattermost Server21Monitor
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
| Product / package | Fixed version | Source |
|---|---|---|
| Go:github.com/mattermost/mattermost-server | 10.11.17 | Package registry (OSV) |
| Go:github.com/mattermost/mattermost-server | 10.11.17+incompatible | Package registry (OSV) |
| Go:github.com/mattermost/mattermost-server | 11.5.5 | Package registry (OSV) |
| Go:github.com/mattermost/mattermost-server | 11.5.5+incompatible | Package registry (OSV) |
| Go:github.com/mattermost/mattermost-server | 11.6.1 | Package registry (OSV) |
| Go:github.com/mattermost/mattermost-server | 11.6.1+incompatible | Package registry (OSV) |
| Go:github.com/mattermost/mattermost/server/v8 | 8.0.0-20260504071740-9408b98025d7 | Package registry (OSV) |
| opensuse:govulncheck-vulndb | 0.0.20260827T195228-160000.1.1 · openSUSE:Leap 16.0 | Package registry (OSV) |
| suse:govulncheck-vulndb | 0.0.20260827T195228-160000.1.1 · SUSE:Linux Enterprise Server 16.0 | Package 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.
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 researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
- 0x7oda7123finder
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
- CVE-2026-634625 days apartSensitive credentials exposed in plaintext in Mattermost support packets34Monitor
- CVE-2026-634725 days apartMattermost Calls plugin exposes TURN server credentials in plaintext in support packets30Monitor
- CVE-2025-13821116 days apartUser profile update exposes password hash and MFA secrets22Monitor
- CVE-2026-60460 days apartPlugin bot username conflict allows user account to be used as bot identity in Mattermost Server21Monitor
- CVE-2025-11794210 days apartPassword hash and MFA secret returned in user email verification endpoint19Monitor
- CVE-2026-363621 days apartSanitize team member data returned by API17Monitor
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
- low · data can be read
- Integrity
- none
- Availability
- none
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality impact
- Low
- Integrity impact
- None
- Availability impact
- None
Weakness class (CWE)
CWE-200 · Exposure of Sensitive Information to an Unauthorized ActorCVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
nvd-secondary
Root cause
The extension requests broader permissions than its function needs and sends the data it collects out for purposes beyond its stated function.
The bug in code
The whole CWE-200 classA representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.
Vulnerable
{ "permissions": ["tabs", "<all_urls>"], "background": { "service_worker": "analytics.js" }}Fixed
{ "permissions": ["activeTab"], "host_permissions": ["https://yildiz.example/*"]}Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
Attack patterns (CAPEC)
- ExcavationCAPEC-116likelihood: High · Medium
- Subverting Environment Variable ValuesCAPEC-13likelihood: High · Very High
- FootprintingCAPEC-169likelihood: High · Very Low
- Exploiting Trust in ClientCAPEC-22likelihood: High · High
- FingerprintingCAPEC-224likelihood: High · Very Low
- ICMP Echo Request PingCAPEC-285likelihood: Medium · Low
- TCP SYN ScanCAPEC-287Low
- Enumerate Mail Exchange (MX) RecordsCAPEC-290Low
ATT&CK techniques
- System Service DiscoveryT1007
- System Network Configuration DiscoveryT1016
- Remote System DiscoveryT1018
- System Owner/User DiscoveryT1033
- Masquerading: Match Legitimate Name or LocationT1036.005
- Network Service ScanningT1046
- System Network Connections DiscoveryT1049
- Process DiscoveryT1057
- Permission Groups DiscoveryT1069
- System Information DiscoveryT1082
- File and Directory DiscoveryT1083
- Account DiscoveryT1087
- Multi-Factor Authentication InterceptionT1111
- Peripheral Device DiscoveryT1120
- System Time DiscoveryT1124
- Access Token Manipulation:Token Impersonation/TheftT1134.001
Change log
- Fix✗ → ✓
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References
Vendor advisories and official records. Exploit/PoC links are deliberately left out.