What is the CVSS score of CVE-2026-20796?

CVE-2026-20796 has a CVSS 3.1 base score of 3.1 (Low). CVSS vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:N. EPSS exploitation probability: 0.0%.

How to fix or mitigate CVE-2026-20796?

During next maintenance window: Apply vendor patches when convenient. Monitor vendor channels for updates.

Mattermost CVE-2026-20796

Q: Which versions of Mattermost are affected by CVE-2026-20796?

CVE-2026-20796 is a low-severity vulnerability (CVSS 3.1). The limited severity suggests constrained impact, typically requiring specific conditions or local access for exploitation.. A patch is available.

LOW

Time-of-check Time-of-use (TOCTOU) Race Condition (CWE-367)

2026-02-13 responsibledisclosure@mattermost.com

GHSA-2xf7-hmf6-p64j

Race Condition Mattermost Mattermost Server

3.1

CVSS 3.1 · NVD

View

Vulnerability Assessment

Weakness	CWE CWE-367 OWASP Top 10:2025 A06:2021 - Vulnerable and Outdated Components ASVS 5.0 V14 - Configuration Dependency management, component inventory
Impact	CVSS 3.1 (LOW). Attack vector: Network. Complexity: High. Privileges required: Low. User interaction: None.
Exploit ScenarioDerived	An attacker could exploit this vulnerability to compromise the affected system.

Monitor Track and reassess. Why: LOW severity (CVSS 0.1-3.9).

Patch available 0.0% exploitation probability (EPSS)

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AnalysisAIv1 – Mar 12, 2026

Mattermost versions 10.11.x <= 10.11.9 fail to properly validate channel membership at the time of data retrieval which allows a deactivated user to learn team names they should not have access to via a race condition in the /common_teams API endpoint.. Mattermost Advisory ID: MMSA-2025-00549 [CVSS 3.1 LOW]

RemediationAI

Monitor vendor advisories for a patch. Restrict network access to the affected service where possible.

Affected Packages

go github.com/mattermost/mattermost-server fix: 10.11.10+incompatible, 10.11.10

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 1 package in go

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

Affects Mattermost Server. Mattermost versions 10.11.x <= 10.11.9 fail to properly validate channel membership at the time of data retrieval which allows a deactivated user to learn team names they should not have access to via a race condition in the /common_teams API endpoint.. Mattermost Advisory ID: MMSA-2025-00549

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Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

NVD PRIMARY 3.1 LOW

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

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

Attack Vector

Network

Attack Complexity

High

Privileges Required

Low

User Interaction

None

Scope

Unchanged

Confidentiality

Low

Integrity

None

Availability

None

Lifecycle Timeline

Patch released

Mar 31, 2026 - 21:13 nvd

Patch available

CVE Published

Feb 13, 2026 - 11:16 nvd

LOW 3.1

DescriptionCVE.org

Executive ViewAI

Why It Matters

CVE-2026-20796 is a low-severity vulnerability (CVSS 3.1). The limited severity suggests constrained impact, typically requiring specific conditions or local access for exploitation. Apply vendor updates when available as part of routine maintenance.

Business Impact: Low

Compensating Controls

Apply vendor patch during routine maintenance. Standard security controls provide adequate interim protection.

Threat Intelligence Overview

EPSS Score

0.0%

Top 99% exploitable

Data Quality

3 sources

Confidence: Low

NVD

CVE.org

EPSS

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue

Severity LOW

CISA KEV No

Public POC No

EPSS 0.0%

Patch available Yes

Active threat No

Deciding rule

LOW severity (CVSS 0.1-3.9)

What every action level means

Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.

Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.

This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.

This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.

Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived

Defer

Exploitation· derived

None

System Exposure· derived

Open

Automatable· derived

Human Impact

Low

Priority Score

Low Medium High Critical

KEV: 0

EPSS: 0

CVSS: +16

PoC: 0

Weaponized: 0

Threat intel: 0

Gov advisory: 0

Attack Technique

Race Condition MEDIUM

Race conditions occur when multiple concurrent requests exploit the brief time gap between checking a condition and acting upon it (TOCTOU - Time of Check, Time of Use).