CVE-2026-26221 | Hyland OnBase contains an unauthenticated .NET Remoting expo… | CVSS 9.8 CRITICAL

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 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.

Metadata

CVE ID: CVE-2026-26221
State: PUBLISHED
Assigner: VulnCheck
Reserved: 2026-02-11 20:08 UTC
Published: 2026-02-13 15:21 UTC
Last updated: 2026-05-25 23:41 UTC
Primary CWE: CWE-502
CWE-502 Deserialization of Untrusted Data
Vendor / Product: Hyland / OnBase Workflow Timer Service
Sources: cve.org · NVD

Severity & Metrics

9.8 CRITICAL CVSS 3.1

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

SSVC — CISA Coordinator

Exploitation: none
Automatable: yes
Tech. Impact: total

Affected products (1)

Vendor	Product	Platform	Versions
Hyland	OnBase Workflow Timer Service	—	8.0 ≤ 17.0.0

Weakness (CWE)

CWE	Source	Description
CWE-502	cna	CWE-502 Deserialization of Untrusted Data

CVSS scores (2)

Score	Severity	Version	Source	Vector
9.8	CRITICAL	3.1	cna	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
9.3	CRITICAL	4.0	cna	CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

References (3)