What’s Vulnerable › Vulnerabilities

CVE-2026-18918: OAuth 1.0 session-fixation chain via unauthenticated provisional-consumer registration and insecure v1_0Allowed default

• Severity: critical (CVSS 9.1 v4.0)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.5% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-08-28 · updated 2026-09-01
• Weakness: CWE-863

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.

Affected products

• Eclipse Foundation Eclipse Lyo: from 2.0.0 before 7.0.0 — fixed in 7.0.0

How to fix

Upgrade to a fixed version: Eclipse Foundation Eclipse Lyo 7.0.0. Check the vendor advisory for mitigations.

References

• https://github.com/eclipse-lyo/lyo/releases/tag/v6.0.1.Final
• https://github.com/eclipse-lyo/lyo/releases/tag/v7.0.0.Beta3
• https://gitlab.eclipse.org/security/cve-assignment/-/work_items/221

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