CVE-2026-8075

Q: How do I fix CVE-2026-8075?

Upgrade Mattermost to 5.13.6 or later.

Q: Is CVE-2026-8075 being actively exploited?

Not that we know of. CVE-2026-8075 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.42% is the estimated probability that it will be exploited in the next 30 days. That is higher than 35% of all scored CVEs.

Q: How severe is CVE-2026-8075?

CVE-2026-8075 has a CVSS v3 base score of 6.5, rated medium. 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-2026-8075 affect?

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

MEDIUM

6.5

CVSS v3

NVD

Description

Mattermost Desktop App versions <=6.2 5.5.13 6.0.2.0 fail to properly null check when checking for headers in the Mattermost Desktop App which allows any user to crash another channel members Desktop App via posting a malicious link with an embedded image that misses one of those headers. Mattermost Advisory ID: MMSA-2026-00668

CWE-754

How to fix

Remediation Available

MattermostWindows application

Affected:5.5.13 5.13.6Fixed in:5.13.6Mattermost, Inc.

Affected:6.2.1 6.3Fixed in:6.3Mattermost, Inc.

Affected:6.0.2 6.2.1Fixed in:6.2.1Mattermost, Inc.

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 ComplexityLow

Privileges RequiredLow

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityNone

IntegrityNone

AvailabilityHigh

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

Exploit Intelligence

0.42%probability of exploitation in 30 days

35thpercentile

Low risk: more likely to be exploited than 35% of all known CVEs.

References

Vendor Advisory1

mattermost.com

Related Vulnerabilities

Other CWE-754 vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2024-4367	High	8.8	71%	-	Fix
CVE-2022-39288	High	7.5	59%	-	Fix
CVE-2023-30591	High	7.5	54%	-	-
CVE-2023-41993	High	8.8	29%	KEV	Fix
CVE-2024-43044	High	8.8	29%	-	Fix
CVE-2024-3393	High	7.5	29%	KEV	Fix

Common questions

How do I fix CVE-2026-8075?

Upgrade Mattermost to 5.13.6 or later.

Is CVE-2026-8075 being actively exploited?

Not that we know of. CVE-2026-8075 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.42% is the estimated probability that it will be exploited in the next 30 days. That is higher than 35% of all scored CVEs.

How severe is CVE-2026-8075?

CVE-2026-8075 has a CVSS v3 base score of 6.5, rated medium. 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-2026-8075 affect?

Published advisories record a fix for Mattermost (Windows application). 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 2026-07-30.