What’s Vulnerable › Vulnerabilities

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

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.5% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-10-14 · updated 2026-10-20
• Weakness: CWE-200

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.

Affected products

• discourse: before 2026.1.9; from 2026.7.0-latest, < 2026.7.3; from 2026.8.0-latest, < 2026.8.1; from 2026.9.0-latest, < 2026.9.0

References

• 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
• https://github.com/discourse/discourse/security/advisories/GHSA-298h-xgw6-4pv3

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