Is CVE-2026-91157 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-91157 being exploited in the wild.

How severe is CVE-2026-91157?

High severity, with a CVSS score of 7.5, published 14 October 2026.

Which products and versions are affected?

Discourse before 2026.9.0, 2026.8.1, 2026.7.3, and 2026.1.9.

Is there a fix for CVE-2026-91157?

Yes: fixed in 2026.9.0, 2026.8.1, 2026.7.3, 2026.1.9. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

How is CVE-2026-91157 attacked?

It is attacked over the network, in a web application.

Am I affected by CVE-2026-91157?

Check whether you run Discourse at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-91157: Discourse insufficient upload security metadata reconciliation

CVE-2026-91157 · Severity: high · CVSS 7.5 · Published 2026-10-14

Discourse is an open-source discussion platform used for community forums and group collaboration. When sites enable secure uploads, the platform failed to update access controls on media files when category permissions changed during bulk imports or when public categories were restricted. This allowed anonymous users to access attachments and media that should have been protected, including files from deleted topics.

Technologies: Discourse. Vendors: Discourse.

Quick answers

Is CVE-2026-91157 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-91157 being exploited in the wild.
How severe is CVE-2026-91157?: High severity, with a CVSS score of 7.5, published 14 October 2026.
Which products and versions are affected?: Discourse before 2026.9.0, 2026.8.1, 2026.7.3, and 2026.1.9.
Is there a fix for CVE-2026-91157?: Yes: fixed in 2026.9.0, 2026.8.1, 2026.7.3, 2026.1.9. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-91157 attacked?: It is attacked over the network, in a web application.
Am I affected by CVE-2026-91157?: Check whether you run Discourse at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

Fixed in: 2026.9.0, 2026.8.1, 2026.7.3, 2026.1.9

Technical details

When category permissions change or during bulk imports, the system does not reconcile existing upload security metadata, leaving uploads with stale public accessibility flags. The vulnerability affects sites with secure uploads enabled and occurs when a previously public category becomes read-restricted or permissions change. Attackers can access uploads through short upload URLs without authentication, including from deleted topics.

Affected products

Discourse Discourse before 2026.9.0, 2026.8.1, 2026.7.3, and 2026.1.9

Timeline

2026-10-14: disclosed
2026-09-22: patched

References

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