CVE-2021-27734

Severity: critical (CVSS 9.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 1.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2021-05-17 · updated 2026-06-17
Weakness: CWE-287

Description

Hirschmann HiOS 07.1.01, 07.1.02, and 08.1.00 through 08.5.xx and HiSecOS 03.3.00 through 03.5.01 allow remote attackers to change the credentials of existing users.

Affected products

Belden Hirschmann HiOS: from 08.1.00 before 08.6.00; 07.1.01, 07.1.02 — fixed in 08.6.00
Belden HiSecOS: from 03.3.00 through 03.5.01

How to fix

Upgrade to a fixed version: Belden Hirschmann HiOS 08.6.00. Check the vendor advisory for mitigations.

References

https://dam.belden.com/dmm3bwsv3/assetstream.aspx?assetid=12914&mediaformatid=50063&destinationid=10016
https://dam.belden.com/dmm3bwsv3/assetstream.aspx?assetid=12914&mediaformatid=50063&destinationid=10016

Get alerted when CVE-2021-27734 or the next vulnerability affects your stack