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CVE-2026-3472— Markdown image rendering bypass in AI bot tool result posts in Mattermost

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是美国Mattermost公司开源的一个开源协作平台。 Mattermost 10.11.3及之前的10.11.x版本、11.6.3及之前的11.6.x版本和11.5.6及之前的11.5.x版本存在处理逻辑错误漏洞，该漏洞源于未能正确应用markdown图像渲染限制，可能导致经过身份验证的攻击者通过向受害者客户端呈现的工具结果内容注入markdown图像语法，将数据泄露到攻击者控制的服务器。

CVSS 3.5 · Low EPSS 0.27% · P18

Affected Version Matrix 7

VendorProduct Version RangeStatus
Mattermost Mattermost 10.11.0≤ 10.11.18 affected
11.6.0≤ 11.6.3 affected
11.5.0≤ 11.5.6 affected
11.7.0 unaffected
10.11.19 unaffected
11.6.4 unaffected
11.5.7 unaffected
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I. Basic Information for CVE-2026-3472

Vulnerability Information
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Vulnerability Title
Markdown image rendering bypass in AI bot tool result posts in Mattermost
Source: CVE Program / CVE List V5
Vulnerability Description
Mattermost versions 10.11.x <= 10.11.18, 11.6.x <= 11.6.3, 11.5.x <= 11.5.6 fail to properly apply markdown image rendering restrictions to AI bot tool result posts, which allows an authenticated attacker to exfiltrate data to an attacker-controlled server via injecting markdown image syntax into tool result content rendered by a victim's client.. Mattermost Advisory ID: MMSA-2026-00619
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:N/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
保护机制失效
Source: CVE Program / CVE List V5
Vulnerability Title
Mattermost 处理逻辑错误漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Mattermost是美国Mattermost公司开源的一个开源协作平台。 Mattermost 10.11.3及之前的10.11.x版本、11.6.3及之前的11.6.x版本和11.5.6及之前的11.5.x版本存在处理逻辑错误漏洞，该漏洞源于未能正确应用markdown图像渲染限制，可能导致经过身份验证的攻击者通过向受害者客户端呈现的工具结果内容注入markdown图像语法，将数据泄露到攻击者控制的服务器。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Mattermost Mattermost 10.11.0 ~ 10.11.18 -

II. Public POCs for CVE-2026-3472

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III. Intelligence Information for CVE-2026-3472

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Same Patch Batch · Mattermost · 2026-06-26 · 4 CVEs total

CVE-2026-9699 6.8 MEDIUM Mattermost Agents plugin logs unsanitized OpenAI API keys on authentication errors
CVE-2026-4339 6.5 MEDIUM SSRF via unvalidated attachment URLs in Mattermost Agents plugin MCP server
CVE-2026-13426 5.4 MEDIUM Client4 fails to validate path parameters

IV. Related Vulnerabilities

Same product: Mattermost
Same vendor: Mattermost
Same weakness: CWE-693

V. Comments for CVE-2026-3472

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