Information disclosure in Getoutline Outline
CVE-2026-28506
Outline is a service that allows for collaborative documentation. Prior to 1.5.0, the events.list API endpoint, used for retrieving activity logs, contains a logic flaw in its filtering mechanism. It allows any authenticated user to retrieve activity events associated with documents that have no collection (e.g., Private Drafts, Deleted Documents), regardless of the user's actual permissions on those documents. While the document content is not directly exposed, this vulnerability leaks sensitive metadata (such as Document IDs, user activity timestamps, and in some specific cases like the Document Title of Permanent Delete). Crucially, leaking valid Document IDs of deleted drafts removes the protection of UUID randomness, making High-severity IDOR attacks (such as the one identified in documents.restore) trivially exploitable by lowering the attack complexity. Version 1.5.0 fixes the issue.
Vulnerability class: Information Disclosure
Published · last modified .
CVSS v3 metric
CVSS v3 base score 4.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N.
EPSS exploit prediction
EPSS: 0.003 (23.2th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 23rd percentile — 23.2% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.002 · newest: 0.003 · change: +0.001
Affected products
- Getoutline Outline
- Outline — versions < 1.5.0
Weakness classification (CWE)
References
- github.com/outline/outline/security/advisories/GHSA-69x7-6fcr-mm6g (Exploit, Vendor Advisory)
Frequently asked questions
- What is CVE-2026-28506?
- CVE-2026-28506 is a medium-severity vulnerability in Getoutline Outline, classified under Information Disclosure. CVSS score: 4.3/10. Published 2026-03-17.
- How severe is CVE-2026-28506?
- Medium severity. CVSS v3 base score is 4.3 out of 10.