CVE-2026-3108

Q: How do I fix CVE-2026-3108?

Upgrade mattermost server to 11.3.2 or later.

Q: Is CVE-2026-3108 being actively exploited?

Not that we know of. CVE-2026-3108 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.28% is the estimated probability that it will be exploited in the next 30 days. That is higher than 20% of all scored CVEs.

Q: How severe is CVE-2026-3108?

CVE-2026-3108 has a CVSS v3 base score of 8.0, rated high. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.

Q: What does CVE-2026-3108 affect?

Published advisories record a fix for mattermost server (NVD). Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.

HIGH

8.0

CVSS v3

NVD

Description

Mattermost versions 11.2.x <= 11.2.2, 10.11.x <= 10.11.10, 11.4.x <= 11.4.0, 11.3.x <= 11.3.1 fail to sanitize user-controlled post content in the mmctl commands terminal output which allows attackers to manipulate administrator terminals via crafted messages containing ANSI and OSC escape sequences that enable screen manipulation, fake prompts, and clipboard hijacking.. Mattermost Advisory ID: MMSA-2026-00599

CWE-150

How to fix

Remediation Available

mattermost serverNVD

Affected:>= 11.3.0, < 11.3.2Fixed in:11.3.2CVE-2026-3108derived from NVD

TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityHigh

Privileges RequiredLow

User InteractionRequired

ScopeChanged

Impact

ConfidentialityHigh

IntegrityHigh

AvailabilityHigh

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

Exploit Intelligence

0.28%probability of exploitation in 30 days

20thpercentile

Low risk: more likely to be exploited than 20% of all known CVEs.

References

Vendor Advisory1

mattermost.com

Related Vulnerabilities

Other CWE-150 vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2017-0899	Critical	9.8	11%	-	Fix
CVE-2025-55754	Critical	9.6	10%	-	Fix
CVE-2021-25310	High	8.8	4.6%	-	-
CVE-2020-6932	Critical	10.0	3.6%	-	-
CVE-2024-28085	Low	3.3	2.2%	-	Fix
CVE-2022-30123	Critical	10.0	1.8%	-	Fix

Common questions

How do I fix CVE-2026-3108?

Upgrade mattermost server to 11.3.2 or later.

Is CVE-2026-3108 being actively exploited?

Not that we know of. CVE-2026-3108 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.28% is the estimated probability that it will be exploited in the next 30 days. That is higher than 20% of all scored CVEs.

How severe is CVE-2026-3108?

CVE-2026-3108 has a CVSS v3 base score of 8.0, rated high. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.

What does CVE-2026-3108 affect?

Published advisories record a fix for mattermost server (NVD). Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-03-30.