OAuth 1.0 session-fixation chain via unauthenticated provisional-consumer registration and insecure v1_0Allowed default
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Attack requirements
- Present
- Impact type
- Security bypass
- Confidentiality · integrity · availability
- High · High · None
- Fix status
- Fixed
Attack profile from CVSS 4.0 · CNA. Fix status from CNA. Impact type from CWE-863.
Summary
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.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- Yes
- Technical impact
- Total
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| Eclipse Foundation | Eclipse Lyo | 2.0.0 to before 7.0.0 | 7.0.0 | Patch available | CNA |
- Eclipse Lyo VendorEclipse Foundation Affected 2.0.0 to before 7.0.0 Fixed in 7.0.0 Patch available CNA
Remediation
- Fix · CNA Eclipse Lyo (Eclipse Foundation) Fixed in 7.0.0
Timeline
- 2026-10-02 Threatist record created from CVE-2026-18918
- 2026-10-03 Alias added: GHSA-jhp3-fv3p-rj5c
References
More Eclipse Foundation vulnerabilities
- TI-2023-23979 The HTTP/2 protocol allows a denial of service (server resource consumption) because… KEVCVSS 3.1HIGH 7.5
- TI-2026-81947 Unauthenticated command injection in Eclipse Che che-machine-exec CVSS 3.1CRITICAL 9.8
- TI-2026-13216 CWE-863: ABAC authorization bypass via trailing slash route normalization in Eclipse BaSyx Go Components CVSS 3.1CRITICAL 9.8
- TI-2026-06514 Path traversal in Eclipse BaSyx CVSS 3.1CRITICAL 10.0
- TI-2026-01382 In the Eclipse Theia Website repository, the GitHub Actions workflow… CVSS 3.1CRITICAL 10.0
- TI-2026-74697 Authentication bypass in Eclipse Jetty EthereumAuthenticator CVSS 4.0CRITICAL 9.3
Sources
- CVE-2026-18918 · CVE Program
- CVE-2026-18918 · NVD
- FIRST EPSS
- GHSA-jhp3-fv3p-rj5c · GitHub Advisory Database · CC BY 4.0
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