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CVE-2026-13417— Boards plugin denial of service via unvalidated block fields.properties

Quick assessment

Affected
Mattermost Mattermost
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Mattermost 版本 11.9.x ≤ 11.9.0、11.8.x ≤ 11.8.4、11.7.x ≤ 11.7.7 以及 10.11.x ≤ 10.11.22 在创建区块时未能校验 的类型，使得拥有看板编辑权限的已认证用户可通过将子区块的 设置为非对象类型的值，导致看板的插件工作进程崩溃，从而触发服务拒绝（DoS）攻击。Mattermost 安全公告编号：MMSA-2026-00710

CVSS 4.3 · Medium
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I. Basic Information for CVE-2026-13417

Vulnerability Information
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Vulnerability Title
Boards plugin denial of service via unvalidated block fields.properties
Source: CVE Program / CVE List V5
Vulnerability 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
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L
Source: CVE Program / CVE List V5
Vulnerability Type
对因果或异常条件的不恰当检查
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
Mattermost Mattermost 11.9.0 ~ 11.9.0 -

II. Public POCs for CVE-2026-13417

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III. Intelligence Information for CVE-2026-13417

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Same Patch Batch · Mattermost · 2026-09-14 · 11 CVEs total

CVE-2026-8821 7.1 HIGH Playbooks run owner channel membership permission bypass
CVE-2026-9812 6.5 MEDIUM Missing property field ownership validation in Playbooks run property update endpoint
CVE-2026-5132 6.5 MEDIUM Unbounded zlib decompression in Calls SDP WebSocket messages
CVE-2026-15814 6.5 MEDIUM Uploading a crafted image causes excessive memory allocation in the Mattermost Server
CVE-2026-10556 5.3 MEDIUM Unauthenticated webhook request with null notification entry could crash the Microsoft Cal
CVE-2026-10542 5.0 MEDIUM Playbooks channel action update validation issue
CVE-2026-14344 4.3 MEDIUM Inconsistent authorization checks in Mattermost Boards endpoints
CVE-2026-12882 4.3 MEDIUM Mattermost Markdown autolink parsing denial of service
CVE-2026-11993 4.3 MEDIUM Fix authenticated members disabling file content indexing server-wide via extraction pool
CVE-2026-14259 4.3 MEDIUM Board archive import bypasses team board creation permissions

IV. Related Vulnerabilities

Same product: Mattermost
Same vendor: Mattermost
Same weakness: CWE-754

V. Comments for CVE-2026-13417

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