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NVD / CVE Program· CNA Mattermost

CVE-2026-2461: Missing authorization check allows unauthorized modification of other users' comments on a board

Noroxi assessment

Priority: Monitor (action score 17/100)

  • Public proof-of-concept code exists (GitHub); there is no record of exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.16% (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) 0.0.0-20260108044135-57c5be5b6ef5; govulncheck-vulndb (openSUSE:Leap 15.6) 0.0.20260326T203309-150000.1.155.2.

Low priority for now. Upgrade to github.com/mattermost/mattermost-plugin-boards (Go) 0.0.0-20260108044135-57c5be5b6ef5; govulncheck-vulndb (openSUSE:Leap 15.6) 0.0.20260326T203309-150000.1.155.2 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 Plugins versions <=11.3 11.0.3 11.2.2 10.10.11.0 fail to implement authorisation checks on comment block modifications, which allows an authorised attacker with editor permission to modify comments created by other board members. Mattermost Advisory ID: MMSA-2025-00559

MediumCVSS 4.3 · v3.1—Proof of concept Fix available
Published
Mar 16, 2026
Updated
Jun 17, 2026
EPSS
0.1% · 6th 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 · 0.1%

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
  • Proof of concept exists, no weaponized module
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2026-2461

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

Affected versions

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

  • mattermost mattermost serverbefore 10.11.11
  • mattermost mattermost server11.0.0 and later · up to 11.0.3 inclusive
  • mattermost mattermost server11.1.0 and later · before 11.2.3
  • mattermost mattermost server11.3.0 and later · before 11.3.1

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

    • 11.4.0, 11.3.1, 11.2.3, 10.11.11not affected
    • up to and including 11.0.3affected · semver
    • up to and including 11.2.2affected · semver
    • up to and including 10.10.11affected · semver

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Gogithub.com/mattermost/mattermost-plugin-boardsbefore 0.0.0-20260108044135-57c5be5b6ef50.0.0-20260108044135-57c5be5b6ef5
openSUSE:Leap 15.6govulncheck-vulndbbefore 0.0.20260326T203309-150000.1.155.20.0.20260326T203309-150000.1.155.2

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-2026-2457Mar 16, 2026 · WebSocket Message Spoofing via Permalink Embed Manipulation
    17Monitor
  • ← EarlierCVE-2026-2458Mar 16, 2026 · Unauthorized channel enumeration in private teams after member removal
    17Monitor
  • Later →CVE-2026-2462Mar 16, 2026 · Admin RCE via Malicious Plugin Upload on CI Test Instances
    26Monitor

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-plugin-boards0.0.0-20260108044135-57c5be5b6ef5Package registry (OSV)
opensuse:govulncheck-vulndb0.0.20260326T203309-150000.1.155.2 · openSUSE:Leap 15.6Package registry (OSV)

Exploit status

Proof of concept available

A public proof of concept or detection signature exists. Exploit knowledge is out there; don't delay patching.

Evidence

  • Proof-of-concept repository on GitHub ×1

Noroxi does not host or link to exploit code. Metasploit module names and Nuclei template ids are shown (names, not code); Exploit-DB entries and PoC repositories are given as counts only.

Public exploit evidence
SourceKindDate
Proof-of-concept repository on GitHubstars:02026-01-30

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.

  1. First PoC-45 d
  2. Published
  3. TodayNov 9, 2026+238 d

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.

Variant candidates

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

  • CVE-2026-347367 days apartImproper file ownership validation in the Boards API allows unauthorised file access
    28Monitor
  • CVE-2025-9081178 days apartIDOR in board file download allows any user to download any file by UUID
    26Monitor
  • CVE-2026-9812182 days apartMissing property field ownership validation in Playbooks run property update endpoint
    26Monitor
  • CVE-2026-606298 days apartIDOR in Jira plugin subscription edit endpoint
    25Monitor
  • CVE-2026-9708119 days apartIncoming webhook user attribution via unvalidated webhook owner
    19Monitor
  • CVE-2026-6541119 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

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
none
Integrity
low · data or configuration can be modified
Availability
none
Attack vector
Network
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality impact
None
Integrity impact
Low
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:N/I:L/A:N

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

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

Fixed

ts
const invoice = await Invoice.findOne({  id: req.params.id,  ownerId: req.user.id,});if (!invoice) return res.sendStatus(404);res.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

  1. Fix✗ → ✓

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

References

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

All records