CVE-2026-18918 OAuth 1.0 session-fixation chain via unauthenticated provisional-consumer registration and insecure v1_0Allowed default
Attackers can bypass OAuth authorization checks in Eclipse Lyo by using unapproved provisional clients when 2-legged auth is enabled.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-18918?
CVE-2026-18918 is a critical authentication bypass vulnerability in Eclipse Lyo, published on 28 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
In Eclipse Lyo versions 2.0.0 to 7.0.0, OAuth server authorization checks can be bypassed when the 2-legged auth is supported by the server. In those cases, application that based their authz filters upon Lyo-provided `AbstractAdapterCredentialsFilter`, are vulnerable. An attacked can create a provisional trusted client (valid use-case) but then it can be used as a trusted client immediately without requiring the administrator approval to clear the provisional status. The 3-legged path requiring user interaction is not vulnerable and rejects provisional clients.
Weakness: CWE-863
Which versions are affected by CVE-2026-18918?
How do I fix CVE-2026-18918?
No fix has been published for CVE-2026-18918 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-2026-18918 being exploited?
There is no known exploitation of CVE-2026-18918 in the wild and no public exploit code.
Sources
Also known as GHSA-jhp3-fv3p-rj5c.