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VulnerabilityPublished Updated

CVE-2026-91157: discourse · Information Exposure

Affects discourseSource CVE Database V5

0

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

CVSS 3.1 base score
7.5High
How severe the flaw is on the 0–10 CVSS scale.
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:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 14 Oct 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq 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

ProductAffectedFixed in
discoursediscourseAffected
  • >=2026.9.0-latest <2026.9.0
Fixed in
  • 2026.9.0
discoursediscourseAffected
  • >=2026.8.0-latest <2026.8.1
Fixed in
  • 2026.8.1
discoursediscourseAffected
  • >=2026.7.0-latest <2026.7.3
Fixed in
  • 2026.7.3
discoursediscourseAffected
  • <2026.1.9
Fixed in
  • 2026.1.9

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

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