NVD / CVE Program· CNA Mattermost

CVE-2026-6062: IDOR in Jira plugin subscription edit endpoint

Noroxi assessment

Priority: Monitor (action score 25/100)

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: 0.24% (FIRST EPSS).
Anyone who can reach it over the internet can trigger it. A low-privileged account is enough. No user action is required. Special conditions such as timing or configuration are required.
Fixed version: github.com/mattermost/mattermost-server (Go) 10.11.18, 10.11.18+incompatible, 11.5.6.

Low priority for now. Upgrade to github.com/mattermost/mattermost-server (Go) 10.11.18, 10.11.18+incompatible, 11.5.6 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 11.7.x <= 11.7.0, 11.6.x <= 11.6.2, 11.5.x <= 11.5.5, 10.11.x <= 10.11.17 Fail to validate channel ownership of an existing subscription before applying edits which allows an authenticated attacker to hijack subscriptions from channels they have no access to via a crafted PUT request to the subscription edit endpoint.. Mattermost Advisory ID: MMSA-2026-00650

MediumCVSS 6.4 · v3.1—No exploit Fix available

Broken access control (IDOR)

Published: Jun 22, 2026
Updated: Jun 23, 2026
EPSS: 0.2% · 15th percentile
CWE: CWE-639

Report tools

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Action score

Monitor

Low priority for now.

CVSS: 25 / 40 · 6.4 / 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: —
CNA · Mattermost: 6.4; 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

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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 server10.11.0 and later · before 10.11.18
mattermost mattermost server11.5.0 and later · before 11.5.6
mattermost mattermost server11.6.0 and later · before 11.6.3
mattermost mattermost server11.7.0 and later · before 11.7.1

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
- 11.8.0, 11.7.1, 11.6.3, 11.5.6, 10.11.18not affected
- 11.7.0 and later · up to and including 11.7.0affected · semver
- 11.6.0 and later · up to and including 11.6.2affected · semver
- 11.5.0 and later · up to and including 11.5.5affected · semver
- 10.11.0 and later · up to and including 10.11.17affected · 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-server	from 10.11.0 · before 10.11.18	10.11.18
Go	github.com/mattermost/mattermost-server	from 10.11.0+incompatible · before 10.11.18+incompatible	10.11.18+incompatible
Go	github.com/mattermost/mattermost-server	from 11.5.0 · before 11.5.6	11.5.6
Go	github.com/mattermost/mattermost-server	from 11.5.0+incompatible · before 11.5.6+incompatible	11.5.6+incompatible
Go	github.com/mattermost/mattermost-server	from 11.6.0 · before 11.6.3	11.6.3
Go	github.com/mattermost/mattermost-server	from 11.6.0+incompatible · before 11.6.3+incompatible	11.6.3+incompatible
Go	github.com/mattermost/mattermost-server	from 11.7.0 · before 11.7.1	11.7.1
Go	github.com/mattermost/mattermost-server	from 11.7.0+incompatible · before 11.7.1+incompatible	11.7.1+incompatible

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-2026-7387Jun 12, 2026 · Mattermost group syncable endpoints allow privilege escalation via scheme_admin
35Monitor
← EarlierCVE-2026-5139Jun 22, 2026 · GitLab Plugin Allows Non-Admin Users to Modify Default Instance Configuration
21Monitor
Later →CVE-2026-6673Jun 22, 2026 · Mattermost Jira plugin had unauthenticated {{/ac/installed}} lifecycle callback during pending Jira Cloud install
25Monitor

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	10.11.18	Package registry (OSV)
Go:github.com/mattermost/mattermost-server	10.11.18+incompatible	Package registry (OSV)
Go:github.com/mattermost/mattermost-server	11.5.6	Package registry (OSV)
Go:github.com/mattermost/mattermost-server	11.5.6+incompatible	Package registry (OSV)
Go:github.com/mattermost/mattermost-server	11.6.3	Package registry (OSV)
Go:github.com/mattermost/mattermost-server	11.6.3+incompatible	Package registry (OSV)
Go:github.com/mattermost/mattermost-server	11.7.1	Package registry (OSV)
Go:github.com/mattermost/mattermost-server	11.7.1+incompatible	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.

0hmzfinder

Variant candidates

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

CVE-2026-347331 days apartImproper file ownership validation in the Boards API allows unauthorised file access
28Monitor
CVE-2026-981284 days apartMissing property field ownership validation in Playbooks run property update endpoint
26Monitor
CVE-2025-9081276 days apartIDOR in board file download allows any user to download any file by UUID
26Monitor
CVE-2026-970821 days apartIncoming webhook user attribution via unvalidated webhook owner
19Monitor
CVE-2026-1010321 days apartAuthenticated remote cluster can modify or delete posts it does not own in Mattermost Connected Workspaces shared channels
17Monitor
CVE-2026-654121 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.
Special conditions such as timing or configuration are required.

If successful

Confidentiality: high · data can be read
Integrity: low · data or configuration can be modified
Availability: low · the service can be disrupted

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

Weakness class (CWE)

CWE-639 · Authorization Bypass Through User-Controlled Key

CVSS vector

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

nvd-secondary

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, 10:46 PM UTC

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References

mattermost.com/security-updates

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

All records