NVD / CVE Program· CNA Mattermost

CVE-2025-9081: IDOR in board file download allows any user to download any file by UUID

Noroxi assessment

Priority: Monitor (action score 26/100)

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: 0.27% (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-plugin-boards (Go) 0.0.0-20250716054606-3f3e3becfe1d; github.com/mattermost/mattermost-server (Go) 10.5.9, 10.5.9+incompatible, 9.11.18; github.com/mattermost/mattermost/server/v8 (Go) 8.0.0-20250721095935-11c36f4d1e44.
Severity is disputed: the assigning authority (CNA) scores it 3.1, NVD 6.5.

Low priority for now. Upgrade to github.com/mattermost/mattermost-plugin-boards (Go) 0.0.0-20250716054606-3f3e3becfe1d; github.com/mattermost/mattermost-server (Go) 10.5.9, 10.5.9+incompatible, 9.11.18; github.com/mattermost/mattermost/server/v8 (Go) 8.0.0-20250721095935-11c36f4d1e44 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 <= 10.5.8, 9.11.x <= 9.11.17 fail to properly validate access controls which allows any authenticated user to download sensitive files via board file download endpoint using UUID enumeration

MediumCVSS 6.5 · v3.1—No exploit Fix available

Broken access control (IDOR)

Published: Sep 19, 2025
Updated: Oct 19, 2026
EPSS: 0.2% · 19th percentile
CWE: CWE-639

Report tools

JSON

Action score

Monitor

Low priority for now.

CVSS: 26 / 40 · 6.5 / 10
CISA KEV: 0 / 30 · Not listed
EPSS: 0 / 30 · 0.2%

CISA SSVC decision

Exploitation: none
Automatable: no
Technical impact: partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD: 6.5
CNA · Mattermost: 3.1; 3.4 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.

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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.

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 server9.11.0 and later · before 9.11.17
mattermost mattermost server10.5.0 and later · before 10.5.9

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
- 10.11.0, 10.5.9, 9.11.18not affected
- 10.5.0 and later · up to and including 10.5.8affected · semver
- 9.11.0 and later · up to and including 9.11.17affected · 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-plugin-boards	before 0.0.0-20250716054606-3f3e3becfe1d	0.0.0-20250716054606-3f3e3becfe1d
Go	github.com/mattermost/mattermost-server	from 10.5.0-rc1 · before 10.5.9	10.5.9
Go	github.com/mattermost/mattermost-server	from 10.5.0-rc1+incompatible · before 10.5.9+incompatible	10.5.9+incompatible
Go	github.com/mattermost/mattermost-server	from 9.11.0-rc1 · before 9.11.18	9.11.18
Go	github.com/mattermost/mattermost-server	from 9.11.0-rc1+incompatible · before 9.11.18+incompatible	9.11.18+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	before 8.0.0-20250721095935-11c36f4d1e44	8.0.0-20250721095935-11c36f4d1e44
openSUSE:Tumbleweed	govulncheck-vulndb	before 0.0.20250924T192141-1.1	0.0.20250924T192141-1.1

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-2025-9084Sep 15, 2025 · Open redirect in OAuth login
24Monitor
← EarlierCVE-2025-9079Sep 19, 2025 · Admin RCE via prepackaged plugins by way of misconfigured imports directory
28Monitor
Later →CVE-2025-41443Oct 16, 2025 · Guest user can discover active public channels
17Monitor

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-plugin-boards	0.0.0-20250716054606-3f3e3becfe1d	Package registry (OSV)
Go:github.com/mattermost/mattermost-server	10.5.9	Package registry (OSV)
Go:github.com/mattermost/mattermost-server	10.5.9+incompatible	Package registry (OSV)
Go:github.com/mattermost/mattermost-server	9.11.18	Package registry (OSV)
Go:github.com/mattermost/mattermost-server	9.11.18+incompatible	Package registry (OSV)
Go:github.com/mattermost/mattermost/server/v8	8.0.0-20250721095935-11c36f4d1e44	Package registry (OSV)
opensuse:govulncheck-vulndb	0.0.20250924T192141-1.1 · openSUSE:Tumbleweed	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.

No history yet (it accumulates with the daily EPSS job).

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.

daw10finder

Variant candidates

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

CVE-2026-3473245 days apartImproper file ownership validation in the Boards API allows unauthorised file access
28Monitor
CVE-2026-9812360 days apartMissing property field ownership validation in Playbooks run property update endpoint
26Monitor
CVE-2026-6062276 days apartIDOR in Jira plugin subscription edit endpoint
25Monitor
CVE-2026-9708297 days apartIncoming webhook user attribution via unvalidated webhook owner
19Monitor
CVE-2026-2461178 days apartMissing authorization check allows unauthorized modification of other users' comments on a board
17Monitor
CVE-2026-6541297 days apartUnscoped updates to other playbooks' metric configuration
17Monitor

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

Mattermost Public Bug Bounty Engagement Bugcrowd · paid · up to $2,000

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: high · data can be read
Integrity: none
Availability: none

Attack vector: Network
Attack complexity: Low
Privileges required: Low
User interaction: None
Scope: Unchanged
Confidentiality impact: High
Integrity impact: None
Availability impact: None

Weakness class (CWE)

CWE-639 · Authorization Bypass Through User-Controlled Key

CVSS vector

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

nvd-primary

Root cause

The endpoint fetches the record by the ID sent in the request, but never checks whether the record belongs to the requesting user.

The bug in code

The whole CWE-639 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

1const invoice = await Invoice.findById(req.params.id);
2res.json(invoice);

Fixed

1const invoice = await Invoice.findOne({
2  id: req.params.id,
3  ownerId: req.user.id,
4});
5if (!invoice) return res.sendStatus(404);
6res.json(invoice);

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.

Change log

Fix✗ → ✓Sep 28, 2026, 10:44 PM UTC

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

References

mattermost.com/security-updates

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

All records