Discourse: Media uploads remain publicly accessible after category permissions are restricted

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-91157
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-10-14 16:17:56 UTC
Updated2026-10-14 16:17:56 UTC
DescriptionDiscourse 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.

Risk And Classification

Primary CVSS: v3.1 7.5 HIGH from [email protected]

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Problem Types: CWE-200 | CWE-863 | CWE-200 CWE-200: Exposure of Sensitive Information to an Unauthorized Actor | CWE-863 CWE-863: Incorrect Authorization

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary7.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
3.1CNADECLARED7.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Discourse Discourse affected < 2026.1.9 Not specified
CNA Discourse Discourse affected >= 2026.7.0-latest, < 2026.7.3 Not specified
CNA Discourse Discourse affected >= 2026.8.0-latest, < 2026.8.1 Not specified
CNA Discourse Discourse affected >= 2026.9.0-latest, < 2026.9.0 Not specified

References

ReferenceSourceLinkTags
github.com/discourse/discourse/commit/b2fb98394b2636b29e850f06b0029f8ca8... [email protected] github.com
github.com/discourse/discourse/commit/16017732981fdb3ee65d7b3c69c573610b... [email protected] github.com
github.com/discourse/discourse/commit/83f5f9f1df7ddc79ec0950e1b2038ba659... [email protected] github.com
github.com/discourse/discourse/commit/98f1c021d0e956cded5239a5d8a6afe2b9... [email protected] github.com
github.com/discourse/discourse/security/advisories/GHSA-298h-xgw6-4pv3 [email protected] github.com
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