CVE-2026-26221

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 OnBase features, this can lead to remote code execution. The same primitive can be abused by supplying a UNC path to coerce outbound NTLM authentication (SMB coercion) to an attacker-controlled host.

CVSS v4.0

9.3 CRITICALCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

CVSS v3.1

9.8 CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS

1.12% chance of exploitation in the next 30 days, 64th percentile

Published

2026-02-13

Updated

2026-05-25

Proof-of-concept exploits (1)

• mbanyamer/CVE-2026-26221-Hyland-OnBase-Timer-Service-Unauthenticated-RCE0★ · 2026-02-18

References

• CVE Record
• NVD entry

Related

• CVE-2019-7711
• CVE-2021-41579
• CVE-2023-31059
• CVE-2025-24076
• CVE-2025-24813
• CVE-2025-30397