CVE-2026-91157: discourse · Information Exposure
Affects discourseSource CVE Database V5
Not known to be exploited · CVSS 7.5 High · fixed in 2026.9.0 : patch discourse soon.
Data as of 26 Oct 2026, 13:47 UTC
- EPSS
- 0.4% chance of exploitation in 30 days – higher than 41% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- CISA SSVC
- Exploitation
- No evidence of active exploitation and no public proof of concept
- Automatable
- Attackers can reliably automate steps 1–4 of the kill chain
- Technical impact
- Limited control over the software or limited information exposure
CISA SSVC assessment, 2026-10-20.
- Patch
- Available – fixed in 2026.9.0, 2026.8.1, 2026.7.3 +1
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:NExploitation evidence
Disclosed: evidence found.
CVE published 14 Oct 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
Upgrade discourse to 2026.9.0, 2026.8.1, 2026.7.3 or 2026.1.9.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| discoursediscourse | Affected
| Fixed in
|
| discoursediscourse | Affected
| Fixed in
|
| discoursediscourse | Affected
| Fixed in
|
| discoursediscourse | Affected
| Fixed in
|
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.
References
- github.com/discourse/discourse/security/advisories/GHSA-298h-xgw6-4pv3 (opens in a new tab)
- github.com/discourse/discourse/commit/16017732981fdb3ee65d7b3c69c573610bf02aab (opens in a new tab)
- github.com/discourse/discourse/commit/83f5f9f1df7ddc79ec0950e1b2038ba659635708 (opens in a new tab)
- github.com/discourse/discourse/commit/98f1c021d0e956cded5239a5d8a6afe2b9e1b7e7 (opens in a new tab)
- github.com/discourse/discourse/commit/b2fb98394b2636b29e850f06b0029f8ca8b48458 (opens in a new tab)