CVE-2026-18918

OAuth 1.0 session-fixation chain via unauthenticated provisional-consumer registration and insecure v1_0Allowed default

Published Aug 28, 2026 CVSS 4.0 · 9.1 Critical EPSS < 1% KEV · Not listed
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}

Type Values Removed Values Added
First Time appeared Eclipse
Eclipse lyo
Vendors & Products Eclipse
Eclipse lyo
Type Values Removed Values Added
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.
Title OAuth 1.0 session-fixation chain via unauthenticated provisional-consumer registration and insecure v1_0Allowed default
Weaknesses CWE-863
References
Metrics cvssV4_0

{'score': 9.1, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/AU:Y/R:U/V:C/RE:L/U:Red'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
eclipse
Published
Updated
Aug 31, 2026, 12:27 PM
Reserved
Aug 5, 2026, 7:44 AM
Status
Deferred
Published
Aug 28, 2026, 12:16 PM
Modified
Sep 1, 2026, 9:11 PM