CVE-2026-54573 Authorization Bypass in API Key/OAuth Scopes via Path Parsing Discrepancy
Attackers can bypass API key scope restrictions by appending fragments to URLs, allowing unauthorized access to restricted endpoints and privilege escalation.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-54573?
CVE-2026-54573 is a medium-severity authentication bypass vulnerability in outline, published on 25 Jun 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
Outline is a service that allows for collaborative documentation. Prior to 1.8.0, the AuthenticationHelper.canAccess function uses ctx.originalUrl to verify if an API key or OAuth token has the required scopes for a request. It extracts the resource by splitting the URL by / and taking the last segment. However, it fails to strip the URL fragment (#). Because Koa's router uses ctx.path (which strips the fragment) for routing, an attacker can append a fragment containing a permitted path (e.g., #foo/api/documents.info) to a restricted endpoint (e.g., /api/documents.create). The router will route the request to the restricted endpoint, but canAccess will evaluate the permitted path in the fragment, bypassing the API key scope restrictions and allowing privilege escalation. This vulnerability is fixed in 1.8.0.
Weakness: CWE-863
Which versions are affected by CVE-2026-54573?
How do I fix CVE-2026-54573?
No fix has been published for CVE-2026-54573 yet. Limit exposure of the affected software until one is available.
Upgrade, and rotate credentials and sessions that may have been exposed. More about Authentication bypass.
Is CVE-2026-54573 being exploited?
There is no known exploitation of CVE-2026-54573 in the wild and no public exploit code.
Sources
Also known as GHSA-5x79-rj4g-qrh8.