CVE-2026-13417

Q: How do I fix CVE-2026-13417?

Upgrade mattermost server to 10.11.23 or later.

Q: Is CVE-2026-13417 being actively exploited?

Not that we know of. CVE-2026-13417 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.37% is the estimated probability that it will be exploited in the next 30 days. That is higher than 31% of all scored CVEs.

Q: How severe is CVE-2026-13417?

CVE-2026-13417 has a CVSS v3 base score of 4.3, 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-2026-13417 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.

MEDIUM

4.3

CVSS v3

NVD

Description

Mattermost versions 11.9.x <= 11.9.0, 11.8.x <= 11.8.4, 11.7.x <= 11.7.7, 10.11.x <= 10.11.22 fail to validate the type of `fields.properties` on block creation which allows an authenticated user with editor access to a board to crash the Boards plugin worker and trigger a denial of service via a child block whose `fields.properties` is a non-object value. Mattermost Advisory ID: MMSA-2026-00710

CWE-754

How to fix

Remediation Available

mattermost serverNVD

Affected:>= 10.11.0, < 10.11.23Fixed in:10.11.23CVE-2026-13417derived from NVD

Affected:>= 11.7.0, < 11.7.8Fixed in:11.7.8CVE-2026-13417derived from NVD

Affected:>= 11.9.0, < 11.9.1Fixed in:11.9.1CVE-2026-13417derived from NVD

Affected:>= 11.8.0, < 11.8.5Fixed in:11.8.5CVE-2026-13417derived 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 ComplexityLow

Privileges RequiredLow

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityNone

IntegrityNone

AvailabilityLow

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

Exploit Intelligence

0.37%probability of exploitation in 30 days

31stpercentile

Low risk: more likely to be exploited than 31% 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	59%	-	-
CVE-2024-3393	High	7.5	29%	KEV	Fix
CVE-2024-43044	High	8.8	29%	-	Fix
CVE-2023-41993	High	8.8	24%	KEV	Fix

Common questions

How do I fix CVE-2026-13417?

Upgrade mattermost server to 10.11.23 or later.

Is CVE-2026-13417 being actively exploited?

Not that we know of. CVE-2026-13417 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.37% is the estimated probability that it will be exploited in the next 30 days. That is higher than 31% of all scored CVEs.

How severe is CVE-2026-13417?

CVE-2026-13417 has a CVSS v3 base score of 4.3, 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-2026-13417 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.

Embed a live status badge for CVE-2026-13417

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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 2026-10-07.