CVE-2021-27734
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...
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.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- High
- Integrity
- High
- Availability
- High
Exploit likelihood
What each source reports
NVD Score used
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.
- Record
CVE-2021-27734- CVSS 3.1
- 9.8 Critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - CVSS 2.0
- 7.5 High
AV:N/AC:L/Au:N/C:P/I:P/A:P - Weakness
- CWE-287
- Updated
- 2026-11-02
CVE List No score
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.
- Record
CVE-2021-27734- Updated
- 2026-11-02
EUVDEUVD-2021-14476 No score
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.
- Record
EUVD-2021-14476- Updated
- 2026-11-03
GitHub AdvisoriesGHSA-r6q8-h627-r6p2
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...
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.
- Record
GHSA-r6q8-h627-r6p2- CVSS 3.1
- 9.8 Critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - Weakness
- CWE-522
- Updated
- 2026-11-02
Affected products
History
| Recorded | Changed | Sources |
|---|---|---|
| aliases | EUVD | |
| first indexed | CVE List, GitHub Advisories, NVD |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2021-27734 is a critical vulnerability (CVSS 9.8) in Belden Hirschmann Hios, published May 17, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 1.26%, the 69th percentile. No source names a fixed version.