CVE-2026-91157 Discourse: Media uploads remain publicly accessible after category permissions are restricted
Attackers can access restricted media uploads via public URLs if category permissions change, exposing private data in Discourse forums.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-91157?
CVE-2026-91157 is a high-severity missing authorization vulnerability in discourse, published on 14 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Which versions are affected by CVE-2026-91157?
1 open source package ship an affected version, including discourse.
| Package | Affected | Fixed in |
|---|---|---|
discourse Bitnami | All versions | 2026.1.9, 2026.7.3, 2026.8.1, 2026.9.0 |
How do I fix CVE-2026-91157?
Upgrade discourse to a fixed version for your release line: 2026.1.9, 2026.7.3, 2026.8.1 or 2026.9.0.
Upgrade, and check permissions on every request on the server, not only in the interface. More about Missing authorization.
Is CVE-2026-91157 being exploited?
There is no known exploitation of CVE-2026-91157 in the wild and no public exploit code.
Sources
Also known as BIT-discourse-2026-91157, GHSA-298h-xgw6-4pv3.