File Upload Vulnerability in Discourse Discussion Platform
CVE-2026-91157

7.5HIGH

Key Information:

Vendor

Discourse
Status
Discourse
Vendor
CVE Published:
14 October 2026

What is CVE-2026-91157?

In the Discourse platform, prior to specified versions, an issue existed where uploads remained publicly accessible even after category permissions changed. This meant that media and attachments uploaded to previously public categories could be accessed by anonymous users, risking sensitive information exposure. The issue was resolved in versions 2026.9.0, 2026.8.1, 2026.7.3, and 2026.1.9, which properly reconciled upload security metadata to restrict access following permission updates.

Affected Version(s)

discourse < 2026.1.9 < 2026.1.9

discourse >= 2026.7.0-latest, < 2026.7.3 < 2026.7.0-latest, 2026.7.3

discourse >= 2026.8.0-latest, < 2026.8.1 < 2026.8.0-latest, 2026.8.1

References

https://github.com/discourse/discourse/security/advisorie...
x_refsource_CONFIRM
https://github.com/discourse/discourse/commit/16017732981...
x_refsource_MISC
https://github.com/discourse/discourse/commit/83f5f9f1df7...
x_refsource_MISC

CVSS V3.1

Score:
7.5
Severity:
HIGH
Confidentiality:
High
Integrity:
None
Availability:
High
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
None
User Interaction:
None
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

.