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CVE-2026-55420— Discourse: Remote code execution via pdf uploads

Quick assessment

Affected
discourse discourse
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.

Discourse是Discourse社区开源的一套开源的社区讨论平台。该平台包括社区、电子邮件和聊天室等功能。 Discourse存在命令注入漏洞，该漏洞源于处理PDF上传时存在命令注入问题，可能导致攻击者在服务器上执行远程代码。以下版本受到影响：2026.6.0之前版本、2026.5.1版本、2026.4.2版本和2026.1.5版本。

CVSS 7.5 · High EPSS 0.35% · P28

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application

Affected Version Matrix 3

VendorProduct Version RangeStatus
discourse discourse >= 2026.5.0-latest, < 2026.5.1 affected
>= 2026.4.0-latest, < 2026.4.2 affected
>= 2026.1.0-latest, < 2026.1.5 affected
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I. Basic Information for CVE-2026-55420

Vulnerability Information
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Vulnerability Title
Discourse: Remote code execution via pdf uploads
Source: CVE Program / CVE List V5
Vulnerability Description
Discourse is an open-source discussion platform. Prior to 2026.6.0, 2026.5.1, 2026.4.2, and 2026.1.5, under certain non-default configurations, processing of PDF uploads could be exploited to obtain RCE on the server. This issue is patched in 2026.6.0, 2026.5.1, 2026.4.2, and 2026.1.5.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
OS命令中使用的特殊元素转义处理不恰当(OS命令注入)
Source: CVE Program / CVE List V5
Vulnerability Title
Discourse 命令注入漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Discourse是Discourse社区开源的一套开源的社区讨论平台。该平台包括社区、电子邮件和聊天室等功能。 Discourse存在命令注入漏洞，该漏洞源于处理PDF上传时存在命令注入问题，可能导致攻击者在服务器上执行远程代码。以下版本受到影响：2026.6.0之前版本、2026.5.1版本、2026.4.2版本和2026.1.5版本。
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
discourse discourse >= 2026.5.0-latest, < 2026.5.1 -

II. Public POCs for CVE-2026-55420

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III. Intelligence Information for CVE-2026-55420

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Patches & Fixes for CVE-2026-55420 (1)

Vendor Advisories for CVE-2026-55420 (1)

Vendor Pages for CVE-2026-55420 (4)

Same Patch Batch · discourse · 2026-07-09 · 11 CVEs total

CVE-2026-44787 8.2 HIGH Discourse: Signup-time primary_group_id assignment grants whisperer access
CVE-2026-53963 7.3 HIGH Discourse: Stored-XSS in 2FA delete confirmation modal
CVE-2026-53961 6.5 MEDIUM Discourse: Forged AWS SNS bounce notifications can disable a targeted user's email (missin
CVE-2026-46413 6.5 MEDIUM Discourse: Regular users can route multipart uploads into the admin backup store
CVE-2026-53962 5.4 MEDIUM Discourse: Insufficient SVG sanitization logic
CVE-2026-45780 5.3 MEDIUM Discourse: Private event sample invitees are serialized to non-invited event viewers
CVE-2026-59828 5.3 MEDIUM Discourse: Hidden post revisions leak through adjacent visible diffs
CVE-2026-45788 Discourse: Secure uploads exposed by hotlinked image copying
CVE-2026-49256 Discourse: Hidden tag names leaked via category serializers
CVE-2026-55424 Discourse: Topic featured link susceptible to stored XSS

IV. Related Vulnerabilities

Same product: discourse
Same vendor: discourse
Same weakness: CWE-78

V. Comments for CVE-2026-55420

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