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CVE-2026-3433

Mattermost doesn't restrict role_updated websocket event broadcasts to members of the affected team or channel

CVSS score

4.3

EPSS probability

%0.3

Risk score

0.0

Published

4 mo ago

Official patch verified

Etkilenen ürün ve sürüm için yayımlanan güvenlik güncellemesini uygulayın.

Impact on My Inventory

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Vulnerability description

DayBreach CVE AI Research

CVE-2026-3433 has vendor, distribution, patch and security-source records on file. We can compare them and prepare an explanation linked to the evidence.

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

IMPACT: Affected Products and Software

Affected Products

The following products are affected by CVE-2026-3433 vulnerability. Where our threat engine knows the exact affected versions, they are listed below.

IDVENDORPRODUCTACTION
1gogithub.com/mattermost/mattermost-server View
2gogithub.com/mattermost/mattermost-server View
3gogithub.com/mattermost/mattermost-server View
4gogithub.com/mattermost/mattermost/server/v8 View
5gogithub.com/mattermost/mattermost-server View
6gogithub.com/mattermost/mattermost-server/v5 View
7gogithub.com/mattermost/mattermost-server/v6 View
8gogithub.com/mattermost/mattermost/server/v8 View
Total affected vendors: 1|Products: 8

RED HAT CSAF/VEX: Product Impact Check

Red Hat has not yet published a CSAF/VEX impact record for this CVE. This does not mean “not affected”.

SCORING: CVSS from Multiple Sources

CVSS Scores

The Common Vulnerability Scoring System is a standardised framework for assessing the severity of vulnerabilities in software and systems. We collect and display CVSS scores from several sources for each CVE.

SCOREVERSIONSEVERITYVECTORSOURCE
4.3CVSS 3.x—Vector not publishedGitHub Advisory
0.0CVSS 4.0—Vector not publishedGitHub Advisory

Patch and Remediation Guide

Solution & Remediation Advisory

Patch verified

4 doğrulanmış yama veya düzeltilmiş sürüm kanıtı bulundu.

osvgithub.com/mattermost/mattermost-server10.11.17+incompatible

OSV düzeltilmiş sürüm: 10.11.17+incompatible

osvgithub.com/mattermost/mattermost-server11.5.5+incompatible

OSV düzeltilmiş sürüm: 11.5.5+incompatible

osvgithub.com/mattermost/mattermost-server11.6.1+incompatible

OSV düzeltilmiş sürüm: 11.6.1+incompatible

osvgithub.com/mattermost/mattermost/server/v88.0.0-20260504071740-9408b98025d7

OSV düzeltilmiş sürüm: 8.0.0-20260504071740-9408b98025d7

Confirm the affected product and version against the source evidence above.
Restrict access to internet-facing services and apply network segmentation.
Apply the official update named in the evidence only to the matching product and version.
Monitor server logs and network endpoints for signs of anomalous execution.

Public exploit and active exploitation status

Verified exploit intelligence

No verified public PoC, exploit repository or Metasploit module has been found for this CVE yet.

Weakness Classification and Attack Patterns (CWE & CAPEC)

CWE - Common Weakness Enumeration

While CVE identifies specific instances of vulnerabilities, CWE categorises the common flaws or weaknesses that can lead to vulnerabilities. CVE-2026-3433 is associated with the following CWEs:

Common Attack Pattern Enumeration and Classification (CAPEC)

Common Attack Pattern Enumeration and Classification (CAPEC) stores attack patterns, which are descriptions of the common attributes and approaches employed by adversaries to exploit the CVE-2026-3433 weaknesses.

Attack Vector and Accessibility

ExposureAğ üzerinden
PermissionsLow
UserGerekmiyor

Official Sources and Advisories

CVSS Vector Radar Chart

4.3 / 10
Attack VectorNetworkComplexityLowPrivilegesLowUser Interact.NoneConfidentialityLowIntegrityNoneAvailabilityNone

Vulnerability Scoring Details

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
Attack VectorNetwork
Attack ComplexityLow
Privileges RequiredLow privileges
User InteractionNone required
Confidentiality (Gizlilik)Low
Integrity (Bütünlük)None
Availability (Erişilebilirlik)None

Yama doğrulandı

4 doğrulanmış yama veya düzeltilmiş sürüm kanıtı bulundu.

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Weakness Type (CWE & CAPEC)

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