Goal Reached Thanks to every supporter — we hit 100%!

Goal: 1000 CNY · Raised: 1359 CNY

100%
Buy Us a Coffee

CVE-2026-6333— SSRF via Host Header Spoofing in Custom Slash Commands

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公司的一个开源协作平台。 Mattermost 11.5.1及之前的11.5.x版本和10.11.13及之前的10.11.x版本存在代码问题漏洞，该漏洞源于构建自定义斜杠命令响应URL时未验证Host标头，可能导致认证攻击者通过伪造的Host标头将斜杠命令响应重定向到攻击者控制的服务器。

CVSS 3.5 · Low EPSS 0.22% · P12

Affected Version Matrix 5

VendorProduct Version RangeStatus
Mattermost Mattermost 11.5.0≤ 11.5.1 affected
10.11.0≤ 10.11.13 affected
11.6.0 unaffected
11.5.2 unaffected
10.11.14 unaffected
Get alerts for future matching vulnerabilities Log in to subscribe

I. Basic Information for CVE-2026-6333

Vulnerability Information
Have questions about the vulnerability? See if Shenlong's analysis helps!
View Shenlong Deep Dive ↗

Although we use advanced large model technology, its output may still contain inaccurate or outdated information.Shenlong tries to ensure data accuracy, but please verify and judge based on the actual situation.

Vulnerability Title
SSRF via Host Header Spoofing in Custom Slash Commands
Source: CVE Program / CVE List V5
Vulnerability Description
Mattermost versions 11.5.x <= 11.5.1, 10.11.x <= 10.11.13 fail to validate the Host header when constructing response URLs for custom slash commands which allows an authenticated attacker to redirect slash command responses to an attacker-controlled server via a spoofed Host header.. Mattermost Advisory ID: MMSA-2026-00582
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:N/I:L/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
服务端请求伪造(SSRF)
Source: CVE Program / CVE List V5
Vulnerability Title
Mattermost 代码问题漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Mattermost是美国Mattermost公司的一个开源协作平台。 Mattermost 11.5.1及之前的11.5.x版本和10.11.13及之前的10.11.x版本存在代码问题漏洞，该漏洞源于构建自定义斜杠命令响应URL时未验证Host标头，可能导致认证攻击者通过伪造的Host标头将斜杠命令响应重定向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 11.5.0 ~ 11.5.1 -

II. Public POCs for CVE-2026-6333

# POC Description Source Link Shenlong Link
AI-Generated POC Premium

No public POC found.

Login to generate AI POC

III. Intelligence Information for CVE-2026-6333

请登录查看更多情报信息。

Same Patch Batch · Mattermost · 2026-05-18 · 21 CVEs total

CVE-2026-6346 8.7 HIGH Sensitive credentials exposed in plaintext in Mattermost support packets
CVE-2026-6347 7.6 HIGH Mattermost Calls plugin exposes TURN server credentials in plaintext in support packets
CVE-2026-3471 6.5 MEDIUM Opening a window with {{javascript:alert()}} as URL causes crash in the Mattermost Desktop
CVE-2026-6345 6.5 MEDIUM Prevent password disclosure and force reset during Slack import
CVE-2026-5163 6.5 MEDIUM Missing authorization check in AI message rewrite endpoint allows access to private thread
CVE-2026-3117 6.5 MEDIUM Instance and webhook GitLab plugin commands were able to be run by non-admin users
CVE-2026-2325 4.3 MEDIUM Improper Input Validation in MS Teams Meetings API Handler
CVE-2026-3637 4.3 MEDIUM Mattermost fails to enforce create_post permission when editing posts
CVE-2026-6342 4.3 MEDIUM Group prefix matching bypass for subscriptions
CVE-2026-6341 4.3 MEDIUM Incomplete group locking implementation
CVE-2026-6340 4.3 MEDIUM Memory Exhaustion via Malicious 7zip File Upload
CVE-2026-6339 4.3 MEDIUM Missing request origin validation on burn-on-read reveal endpoint
CVE-2026-28759 4.3 MEDIUM Insufficient authorization in shared channel membership sync allows remote cluster to remo
CVE-2026-6343 4.3 MEDIUM Mattermost Playbooks Plugin fails to enforce view permissions in list endpoints, allowing
CVE-2026-28732 4.3 MEDIUM Slash command trigger-word update allowed command hijacking
CVE-2026-3495 3.8 LOW Unescaped variables during error page composition
CVE-2026-4273 3.7 LOW Insufficient token rotation validation in remote cluster invite confirmation
CVE-2026-4643 3.5 LOW Calling window.close() from server-side content causes crash in the Mattermost Desktop App
CVE-2026-4286 3.1 LOW Playbooks Plugin fails to validate team transfers, allowing unauthorized removal of member
CVE-2026-6334 3.1 LOW OAuth authorization code client binding not enforced during token redemption in Mattermost

IV. Related Vulnerabilities

Same product: Mattermost
Same vendor: Mattermost
Same weakness: CWE-918

V. Comments for CVE-2026-6333

No comments yet

Leave a comment