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CVE-2026-91157— Discourse: Media uploads remain publicly accessible after category permissions are restricted

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 是一个开源的讨论平台。在版本 2026.9.0、2026.8.1、2026.7.3 和 2026.1.9 之前，当先前公开的分类转变为仅读权限限制，或者在批量导入过程中分类权限发生变化时，启用了安全上传功能的站点未能重新校验现有上传的安全元数据。在分类为公开状态期间上传的媒体文件和附件，其公开访问标志未更新，仍然可通过其短上传 URL 被匿名用户访问，包括与已删除主题关联的上传文件。该问题已在版本 2026.9.0、2026.8.1、2026.7.3 和 2026.1.9 中得到修复。

CVSS 7.5 · High EPSS 0.48% · P40

Possible ATT&CK Techniques 1 AI

T1530 · Data from Cloud Storage

Affected Version Matrix 4

VendorProduct Version RangeStatus
discourse discourse < 2026.1.9 affected
>= 2026.7.0-latest, < 2026.7.3 affected
>= 2026.8.0-latest, < 2026.8.1 affected
>= 2026.9.0-latest, < 2026.9.0 affected
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I. Basic Information for CVE-2026-91157

Vulnerability Information
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Vulnerability Title
Discourse: Media uploads remain publicly accessible after category permissions are restricted
Source: CVE Program / CVE List V5
Vulnerability Description
Discourse is an open-source discussion platform. Prior to 2026.9.0, 2026.8.1, 2026.7.3, and 2026.1.9, sites with secure uploads enabled did not reconcile existing upload security metadata when a previously public category became read-restricted or when category permissions changed during a bulk import. Media and attachments uploaded while the category was public retained a public accessibility flag and remained reachable by anonymous users through their short upload URLs, including uploads associated with deleted topics. This issue is fixed in versions 2026.9.0, 2026.8.1, 2026.7.3, and 2026.1.9.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
信息暴露
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
discourse discourse < 2026.1.9 -

II. Public POCs for CVE-2026-91157

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III. Intelligence Information for CVE-2026-91157

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Patches & Fixes for CVE-2026-91157 (4)

Other References for CVE-2026-91157 (1)

Same Patch Batch · discourse · 2026-10-14 · 3 CVEs total

CVE-2026-91159 7.7 HIGH Discourse: Stored oEmbed HTML injection via allowed iframe
CVE-2026-91156 7.5 HIGH Discourse: Chat MessageBus delivers read-restricted messages to unauthorized users

IV. Related Vulnerabilities

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

V. Comments for CVE-2026-91157

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