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CVE-2026-49256— Discourse: Hidden tag names leaked via category serializers

AI Predicted 5.3 Difficulty: Easy EPSS 0.37% · P30

Possible ATT&CK Techniques 1AI

T1530 · Data from Cloud Storage

Affected Version Matrix 3

VendorProductVersion RangeStatus
discoursediscourse>= 2026.1.0-latest, < 2026.1.5affected
>= 2026.4.0-latest, < 2026.4.2affected
>= 2026.5.0-latest, < 2026.5.1affected
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I. Basic Information for CVE-2026-49256

Vulnerability Information
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Vulnerability Title
Discourse: Hidden tag names leaked via category serializers
Source: NVD (National Vulnerability Database)
Vulnerability Description
Discourse is an open-source discussion platform. Prior to 2026.6.0, 2026.5.1, 2026.4.2, and 2026.1.5, restricted tag and tag-group names attached to publicly readable categories as allowed_tags, allowed_tag_groups, or required tag groups could leak to anonymous and unauthorized users through category and group endpoints. This issue is fixed in versions 2026.6.0, 2026.5.1, 2026.4.2, and 2026.1.5.
Source: NVD (National Vulnerability Database)
CVSS Information
N/A
Source: NVD (National Vulnerability Database)
Vulnerability Type
信息暴露
Source: NVD (National Vulnerability Database)
Vulnerability Title
Discourse 信息泄露漏洞
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 2026.1.5之前版本、2026.4.2之前版本、2026.5.1之前版本和2026.6.0之前版本存在信息泄露漏洞，该漏洞源于受限标签和标签组名称泄露，可能导致匿名用户和未授权用户通过类别和组端点获取信息。
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

VendorProductAffected VersionsCPESubscribe
discoursediscourse >= 2026.1.0-latest, < 2026.1.5 -

II. Public POCs for CVE-2026-49256

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III. Intelligence Information for CVE-2026-49256

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Vendor Advisories for CVE-2026-49256 (1)

Vendor Pages for CVE-2026-49256 (4)

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

CVE-2026-447878.2 HIGHDiscourse: Signup-time primary_group_id assignment grants whisperer access
CVE-2026-554207.5 HIGHDiscourse: Remote code execution via pdf uploads
CVE-2026-539637.3 HIGHDiscourse: Stored-XSS in 2FA delete confirmation modal
CVE-2026-539616.5 MEDIUMDiscourse: Forged AWS SNS bounce notifications can disable a targeted user's email (missin
CVE-2026-464136.5 MEDIUMDiscourse: Regular users can route multipart uploads into the admin backup store
CVE-2026-539625.4 MEDIUMDiscourse: Insufficient SVG sanitization logic
CVE-2026-457805.3 MEDIUMDiscourse: Private event sample invitees are serialized to non-invited event viewers
CVE-2026-598285.3 MEDIUMDiscourse: Hidden post revisions leak through adjacent visible diffs
CVE-2026-45788Discourse: Secure uploads exposed by hotlinked image copying
CVE-2026-55424Discourse: Topic featured link susceptible to stored XSS

IV. Related Vulnerabilities

Same product: discourse
Same vendor: discourse
Same weakness: CWE-200

V. Comments for CVE-2026-49256

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