CVE-2026-91157 Discourse - Broken Access Control

Discourse < 2026.9.0, 2026.8.1, 2026.7.3, and 2026.1.9 contains an information disclosure vulnerability caused by improper reconciliation of upload security metadata when category permissions change, letting anonymous users access restricted media via short URLs, exploit requires secure uploads enabled and category permission changes.

CVSS base score 7.5 /10
High
CISA KEV
Not listed
Public exploit
None known
Authentication
Not required
View the NVD record ↗

Details

Type
Broken Access Control
Impact
Information Disclosure
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Published
14 October 2026
Updated
15 October 2026
Weakness
CWE-200

Vendor fix

Update to versions 2026.9.0, 2026.8.1, 2026.7.3, or 2026.1.9.

Patching closes this CVE. It does not tell you which of your systems run the affected version, or what else is exposed alongside them.

References

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