Security readout for executives and security teams
Plain-English summary
Eclipse Lyo applications may let an unauthenticated attacker create a provisional client and immediately use it as trusted, bypassing administrator approval. The issue can expose protected information or permit unauthorized changes when the application supports two-legged OAuth and relies on Lyo’s affected authorization filter. The user-interactive three-legged OAuth path is reported unaffected.
Executive priority
Treat affected, externally reachable two-legged OAuth deployments as an immediate remediation priority because successful bypass can compromise sensitive data and permit unauthorized changes. First establish whether the required configuration exists; unaffected three-legged-only deployments can receive lower priority. Obtain confirmed upgrade or mitigation instructions from Eclipse because the supplied bundle does not explicitly name a fixed version.
Technical view
CVE-2026-18918 is a CWE-863 authorization failure affecting Eclipse Lyo versions 2.0.0 through 7.0.0 under specific conditions. A provisional consumer can bypass approval when two-legged OAuth is enabled and authorization filters derive from AbstractAdapterCredentialsFilter. The supplied CVSS 4.0 score is 9.1, reflecting network reachability, no required privileges or user interaction, and high confidentiality and integrity impact.
Likely exposure
Exposure requires all cited conditions: an affected Lyo version, server support for two-legged OAuth, and authorization based on AbstractAdapterCredentialsFilter. Internet-accessible authorization endpoints increase practical exposure. Deployments using only the three-legged, user-interactive path are reported not vulnerable. The bundle’s structured affected-version entry conflicts with its narrative range, so inventories should verify vendor records.
Exploitation context
The source bundle does not report active exploitation, and the CVE is not listed as KEV. Exploitation requires a particular server configuration but reportedly needs neither prior authentication nor user interaction. No evidence in the supplied sources establishes public exploit availability, observed attacks, or widespread vulnerable deployment.
Researcher notes
The described trust-boundary failure is narrower than a universal OAuth bypass: it depends on two-legged support and Lyo-based filtering. The title references session fixation and an insecure v1_0Allowed default, but the supplied description does not fully explain those mechanics. Release links are provided without explicit fix statements. Avoid inferring that either referenced release is patched without confirming its advisory details.
Mitigation direction
- Identify Eclipse Lyo deployments and prioritize those exposing OAuth services to untrusted networks.
- Disable two-legged OAuth where operationally feasible until authoritative vendor guidance is applied.
- Ensure provisional consumers cannot act as trusted clients before explicit administrator approval.
- Review the cited Eclipse Lyo releases and CVE record for confirmed fixed versions or configuration guidance.
- Restrict OAuth authorization endpoints and monitor provisional-client registration while remediation is pending.
Validation and detection
- Record each deployment’s exact Eclipse Lyo version and compare it with the reported 2.0.0–7.0.0 range.
- Confirm whether the OAuth server supports or enables two-legged authentication.
- Inspect authorization filters for inheritance from or reliance on AbstractAdapterCredentialsFilter.
- Verify that provisional consumers remain unusable until an administrator clears provisional status.
- Review logs for unexpected provisional registrations or immediate trusted-client activity.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-863: Authorization and privilege behavior lookup
Authorization weaknesses can support privilege escalation and valid-account review, depending on exploit path. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCVE-2026-18918 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Critical
- CVSS
- 9.1 (4.0)
- Known Exploited
- No
- Published
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
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
SSVC decision data
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
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——eclipseVulnerability scoring details
Base CVSS 4.0 score
9.1CriticalVector: 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
Vulnerability timeline
Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.
- CVE reservedCVE Program
The CVE ID was reserved by the assigning CNA.
- CVE publishedCVE Program
The CVE record was published.
- CVE updatedCVE Program
The CVE record metadata indicates this as the latest update time.
ADP provider summaries
Source materials
- CVE List V5 sourceCVE List V5
- https://github.com/eclipse-lyo/lyo/releases/tag/v6.0.1.FinalCVE reference, eclipse
- https://github.com/eclipse-lyo/lyo/releases/tag/v7.0.0.Beta3CVE reference, eclipse
- https://gitlab.eclipse.org/security/cve-assignment/-/work_items/221CVE reference, eclipse
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Incorrect Authorization
Incorrect Authorization represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.