Privilege escalation in Outline

CVE-2026-43886

Outline is a service that allows for collaborative documentation. From 0.84.0 to 1.6.1, a logic error in OAuthInterface.validateScope() uses Array.some() to validate requested OAuth scopes, causing the function to accept the entire scope array if any single scope is valid. An attacker can smuggle the wildcard * scope by requesting scope=read *, escalating a read-only OAuth token to full unrestricted API access including write, delete, and admin operations. This vulnerability is fixed in 1.7.0.

Vulnerability class: Privilege Escalation

Published · last modified .

CVSS v3 metric

CVSS v3 base score 8.2 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:H/A:N.

EPSS exploit prediction

EPSS: 0.003 (20.7th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 21st percentile — 20.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2026-43886: held from 0.002 to 0.003.

EPSS over last 30 days · oldest: 0.002 · newest: 0.003 · change: +0.001

Affected products

  • Outline — versions >= 0.84.0, < 1.7.0

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-43886?
CVE-2026-43886 is a high-severity vulnerability in Outline, classified under Improper Privilege Management. CVSS score: 8.2/10. Published 2026-05-11.
How severe is CVE-2026-43886?
High severity. CVSS v3 base score is 8.2 out of 10.