CVE-2026-26221Network attack vector

Unauthenticated code execution via unsafe object unmarshalling

Published Feb 13, 2026 · Updated Feb 13, 2026

Unsafe deserialization in Hyland OnBase Workflow Timer Service 8.0 through 17.0.0 allows remote attackers to execute arbitrary code. The default HTTP channel on TCP/8900 passes crafted requests to TimerServiceAPI.rem or TimerServiceEvents.rem for unsafe object unmarshalling, enabling arbitrary file reads and writes. Network reachability without authentication is sufficient; writes to web-accessible locations or feature chaining enable code execution, while UNC paths can coerce outbound NTLM authentication.

CVSS severity9.3
Critical
EPSS probability1.16%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Unsafe deserialization in Hyland OnBase Workflow Timer Service 8.0 through 17.0.0 allows remote attackers to execute arbitrary code. The default HTTP channel on TCP/8900 passes crafted requests to TimerServiceAPI.rem or TimerServiceEvents.rem for unsafe object unmarshalling, enabling arbitrary file reads and writes. Network reachability without authentication is sufficient; writes to web-accessible locations or feature chaining enable code execution, while UNC paths can coerce outbound NTLM authentication.

The record

CVE
CVE-2026-26221
Published
Feb 13, 2026
Updated
Feb 13, 2026
Vendor
Hyland
Product
OnBase Workflow Timer Service
Classifications
CWE-502, T1210
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 13, 2026CVE publishedPublication date reported by the CVE source.
  2. Feb 13, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=8.0 <=17.0.x

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Hyland · OnBase Workflow Timer Serviceversion=8.0 <=17.0.x

Published CVSS scores

9.3VulnCheckCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
9.8VulnCheckCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-502Deserialization of Untrusted Data
T1210Exploitation of Remote Services

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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