CVE-2026-39310
Published: 20 May 2026
Summary
CVE-2026-39310 is a high-severity Improper Access Control (CWE-284) vulnerability. Its CVSS base score is 8.6 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked at the 31.0th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-31156
Vulnerability details
Trilium Notes is a cross-platform, hierarchical note taking application focused on building large personal knowledge bases. In versions 0.102.1 and prior, the Clipper API in Trilium Desktop (v0.101.3) allows full authentication bypass when running in an Electron environment. When Trilium…
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detects an Electron environment, it explicitly disables authentication middleware for the Clipper API, exposing endpoints such as /api/clipper/notes to the network with no password, API token, or CSRF protection. An attacker on a shared network (for example, a corporate LAN or public Wi-Fi) can scan for open high-range ports using a tool like nmap, since Trilium often binds to ports such as 37840. Once a candidate port is found, an unauthenticated request to the Clipper handshake endpoint, which also bypasses authentication, confirms a Trilium instance by returning the application name and protocol version. This facilitates unauthorized data access, phishing, and local system compromise. The issue has been fixed in version 0.102.2.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Authentication bypass exposes network-accessible Clipper API endpoints without protection, directly enabling remote exploitation of a public-facing service.
CVEs Like This One
Affected Assets
Mitigating Controls
Likely Mitigating Controls AI
Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.
Device lock enforces restricted access until re-authentication, directly reducing unauthorized use of active sessions.
Explicitly identifying and documenting actions permitted without identification or authentication enforces proper access control boundaries by defining justified exceptions.
Requiring authorization and configuration controls for mobile device connections directly enforces access control and prevents unauthorized devices from reaching organizational systems.
Provides a tamperproof, always-invoked, and verifiable mechanism to enforce access control policies.
Provides capability to review session content, directly detecting violations of access control.
Control assessments verify that access controls are implemented correctly and operating as intended, detecting improper access control before exploitation.
Certification requires independent assessment confirming access controls are implemented correctly and effective.
Restricting available functions and services reduces the attack surface and enforces proper access control boundaries.