CRITICAL

CVE-2026-26221

Hyland OnBase Timer Service Unauthenticated .NET Remoting RCE

CVSS v3

9.8

CRITICAL

EPSS Score

1.4 %

exploit probability, as of 2026-09-25

CISA KEV

known exploited

Exploitation

none

SSVC status

Description

Hyland OnBase contains an unauthenticated .NET Remoting exposure in the OnBase Workflow Timer Service (Hyland.Core.Workflow.NTService.exe). An attacker who can reach the service can send crafted .NET Remoting requests to default HTTP channel endpoints on TCP/8900 (e.g., TimerServiceAPI.rem and TimerServiceEvents.rem for Workflow) to trigger unsafe object unmarshalling, enabling arbitrary file read/write. By writing attacker-controlled content into web-accessible locations or chaining with other

Technical details

Published: 2026-02-13
Last Modified: 2026-04-14

Frequently asked questions

What is CVE-2026-26221?

Is CVE-2026-26221 actively exploited?

Active exploitation of CVE-2026-26221 has not been confirmed. Its EPSS score was 1.4% on 2026-09-25, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2026-26221?

CVE-2026-26221 has a CVSS v3 base score of 9.8 (CRITICAL severity).

Is CVE-2026-26221 affecting your environment?

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