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NVD / CVE Program· CNA Mattermost

CVE-2025-10545: Guest user can add unauthorized team users to private channels

MediumCVSS 4.3 · v3.1—No exploit Fix available

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: 0.33% (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) 10.11.3, 10.11.3+incompatible, 10.5.11; github.com/mattermost/mattermost/server/v8 (Go) 8.0.0-20250820115038-ff30b84049f0.

Low priority for now. Upgrade to github.com/mattermost/mattermost-server (Go) 10.11.3, 10.11.3+incompatible, 10.5.11; github.com/mattermost/mattermost/server/v8 (Go) 8.0.0-20250820115038-ff30b84049f0 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 10.5.x <= 10.5.10, 10.11.x <= 10.11.2 fail to properly validate guest user permissions when adding channel members which allows guest users to add any team members to their private channels via the `/api/v4/channels/{channel_id}/members` endpoint

Published
Oct 16, 2025
Updated
Oct 19, 2026
EPSS
0.3% · 27th percentile

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
4.3
CNA · Mattermost
3.1
1.2 point gap

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

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.

Follow CVE-2025-10545

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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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.

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Affected 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.

VendorProduct
mattermostmattermost server

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

    • 10.12.0, 10.5.11, 10.11.3not affected
    • 10.5.0 and later · up to and including 10.5.10affected · semver
    • 10.11.0 and later · up to and including 10.11.2affected · semver

Affected versions

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

  • mattermost mattermost server10.5.0 and later · before 10.5.11
  • mattermost mattermost server10.11.0 and later · before 10.11.3

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 10.11.310.11.3
Gogithub.com/mattermost/mattermost-serverfrom 10.11.0+incompatible · before 10.11.3+incompatible10.11.3+incompatible
Gogithub.com/mattermost/mattermost-serverfrom 10.5.0 · before 10.5.1110.5.11
Gogithub.com/mattermost/mattermost-serverfrom 10.5.0+incompatible · before 10.5.11+incompatible10.5.11+incompatible
Gogithub.com/mattermost/mattermost-server/v5from 0—
Gogithub.com/mattermost/mattermost-server/v6from 0—
Gogithub.com/mattermost/mattermost/server/v8before 8.0.0-20250820115038-ff30b84049f08.0.0-20250820115038-ff30b84049f0

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

Published before and after this one in the same product

  • ← EarlierCVE-2025-9081Sep 19, 2025 · IDOR in board file download allows any user to download any file by UUID
    26Monitor
  • ← EarlierCVE-2025-41443Oct 16, 2025 · Guest user can discover active public channels
    17Monitor
  • Later →CVE-2025-41410Oct 16, 2025 · Slack import bypasses email verification for team access controls
    21Monitor

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-server10.11.3Package registry (OSV)
Go:github.com/mattermost/mattermost-server10.11.3+incompatiblePackage registry (OSV)
Go:github.com/mattermost/mattermost-server10.5.11Package registry (OSV)
Go:github.com/mattermost/mattermost-server10.5.11+incompatiblePackage registry (OSV)
Go:github.com/mattermost/mattermost/server/v88.0.0-20250820115038-ff30b84049f0Package 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.

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-2025-25274209 days apartUnauthorized Command Execution in Archived Channels
    35Monitor
  • CVE-2026-7387239 days apartMattermost group syncable endpoints allow privilege escalation via scheme_admin
    35Monitor
  • CVE-2026-9816305 days apartInsufficient server-side validation of board member role fields permits privilege escalation
    33Monitor
  • CVE-2026-6739239 days apartMattermost: Delegated admins could patch protected default system roles
    28Monitor
  • CVE-2026-2462151 days apartAdmin RCE via Malicious Plugin Upload on CI Test Instances
    26Monitor
  • CVE-2025-30179209 days apartMFA Enforcement Bypass in Search APIs
    26Monitor

Bug bounty scope

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

Not on record for this CVE: EPSS history · patch commit or PR link.

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-863 · Incorrect Authorization

CVSS vector

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

nvd-primary

Attack context

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

MITRE has no CAPEC/ATT&CK mapping for this CWE.

References

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

All records