Medium · CVSS 4.3CVE-2026-13417

Boards plugin denial of service via unvalidated block fields.propertiesCVE-2026-13417

Answer in brief

CVE-2026-13417 records a Medium severity (CVSS 4.3) vulnerability in Boards plugin denial of service via unvalidated block fields.properties. The current sources do not mark it as known exploited. The current feed maps Mattermost/Mattermost (generic), Mattermost/Mattermost (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Sep 14, 2026Updated Oct 7, 2026Source checked Oct 29, 2026First seen by HOL Sep 14, 2026Material review Oct 7, 2026

Upstream Advisory

Key facts

Risk: Medium · CVSS 4.3
Exploitation: Not marked as known exploited
Affected software: 3 mapped packages or products
Fix availability: Not reported

Why this deserves its current priority

CVSS is 4.3. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps Mattermost/Mattermost (generic), Mattermost/Mattermost (generic). Check affected ranges and fixed versions before updating.

Affected products and reported versions
Product	Affected versions	Fixed versions
cpe:2.3:a:mattermost:mattermost_server::::::::	Not reported	Not reported

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
Mattermost/Mattermostgeneric	>=11.9.0 <=11.9.0 \|\| >=11.8.0 <=11.8.4 \|\| >=11.7.0 <=11.7.7 \|\| >=10.11.0 <=10.11.22	Not reported
Mattermost/Mattermostgeneric	11.9.0 \|\| 11.8.0 \|\| 11.7.0 \|\| 10.11.0	Not reported

Recommended response

Check inventory. Check lockfiles and deployed manifests for Mattermost/Mattermost, Mattermost/Mattermost.
Review the reported fix. Source-reported solution: Update Mattermost to versions 11.10.0, 11.9.1, 11.8.5, 11.7.8, 10.11.23 or higher.

Evidence timeline and material changes

Published upstream
Sep 14, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Oct 7, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Sep 14, 2026

Sources and claim methodology

Source referencemattermost.com

Upstream source 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

Quoted source text, attributed separately from HOL analysis.