CVE-2026-91157Network attack vectorHinoki check available

Media disclosure via stale public upload flags

Published Oct 14, 2026 · Updated Oct 14, 2026

Information disclosure in Discourse upload handling allows remote attackers to read restricted media through public short upload URLs. Category permission changes fail to reconcile existing upload security metadata, leaving previously public attachments accessible anonymously, including those in deleted topics. Exposure requires secure uploads enabled and a previously public category becoming read-restricted, or category permissions changing during a bulk import.

CVSS severity7.5
High
EPSS probability0.48%
Next 30 days · Oct 19, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkAvailable
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Summary

What happened

Information disclosure in Discourse upload handling allows remote attackers to read restricted media through public short upload URLs. Category permission changes fail to reconcile existing upload security metadata, leaving previously public attachments accessible anonymously, including those in deleted topics. Exposure requires secure uploads enabled and a previously public category becoming read-restricted, or category permissions changing during a bulk import.

The record

CVE
CVE-2026-91157
Published
Oct 14, 2026
Updated
Oct 14, 2026
Vendor
Discourse
Product
Discourse
Classifications
Unavailable
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Oct 14, 2026CVE publishedPublication date reported by the CVE source.
  2. Oct 14, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 2026.1.9
  2. Affected versionversion=>= 2026.7.0-latest, < 2026.7.3
  3. Affected versionversion=>= 2026.8.0-latest, < 2026.8.1
  4. Affected versionversion=>= 2026.9.0-latest, < 2026.9.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Discourse · Discourseversion=< 2026.1.9; version=>= 2026.7.0-latest, < 2026.7.3; version=>= 2026.8.0-latest, < 2026.8.1; version=>= 2026.9.0-latest, < 2026.9.0

Published CVSS scores

7.5DiscourseCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Activity data is delayed. The latest report is Sep 28, 2026.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 22, 2026Sep 28, 2026
Latest reporting daySep 28, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

No sourced classifications are available.

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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