SIMATIC IPC BX-21A: Use of Default Cryptographic Key
CVE-2026-72895 is a high-severity use of default cryptographic key vulnerability in SIMATIC IPC BX-21A from Siemens, with a CVSS 3.1 base score of 7.7 out of 10. It can be exploited with local access to the system by an unauthenticated attacker, but only if a user takes part, for example by opening a link or file. The record lists version V31.01.13 as the first without the flaw, so updating SIMATIC IPC BX-21A to that release or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.11% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update SIMATIC IPC BX-21A to V31.01.13 or a later version.
- Update SIMATIC IPC RW-543A to V1.1.4 or a later version.
- Update SIMATIC IPC227G / IPC277G / IPC277G PRO / IPC327G / IPC377G to V28.01.15 or a later version.
- Because the attack needs a user to take part, warn users about unexpected links and files related to this product until it is patched.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Siemens | SIMATIC IPC BX-21A | before V31.01.13 | V31.01.13 |
| Siemens | SIMATIC IPC RW-543A | before V1.1.4 | V1.1.4 |
| Siemens | SIMATIC IPC227G / IPC277G / IPC277G PRO / IPC327G / IPC377G | before V28.01.15 | V28.01.15 |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- LocalThe attacker needs local access or must trick a user into running something.
- Attack complexity
- HighSuccess depends on conditions outside the attacker's control.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- RequiredA user must take an action such as opening a file or link.
- Scope
- ChangedThe attack can reach beyond the vulnerable component into other systems.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:C/C:H/I:H/A:H. Scored by CNA (siemens.com).
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 4.0 | 8.4 | High | CNA (siemens.com) |
| CVSS 3.1 | 7.7 | High | CNA (siemens.com) |
Official description
A vulnerability has been identified in SIMATIC IPC BX-21A (All versions < V31.01.13), SIMATIC IPC RW-543A (All versions < V1.1.4), SIMATIC IPC227G / IPC277G / IPC277G PRO / IPC327G / IPC377G (All versions < V28.01.15). A BIOS vendor test key is present in the UEFI Secure Boot key database. This could allow a local attacker with physical or administrative access to the device to boot an operating system or UEFI application signed with that test key, bypassing UEFI Secure Boot protections even when Secure Boot is enabled, potentially leading to a full loss of confidentiality, integrity, and availability of the device.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Use of Default Cryptographic Key
The product uses a default cryptographic key for potentially critical functionality.
How developers prevent this class of flaw
- Prohibit use of default, hard-coded, or other values that do not vary for each installation of the product - especially for separate organizations.
- Force the administrator to change the credential upon installation.
- The product administrator could change the defaults upon installation or during operation.
More Use of Default Cryptographic Key vulnerabilities (CWE-1394)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Other references
Other vulnerabilities in SIMATIC IPC BX-21A
- 8.2 High severity
- 8.2 High severity
Recent Use of Default Cryptographic Key vulnerabilities
- 8.8 High severity
- 9.1 Critical severity
- 9.8 Critical severity
- 8.1 High severity
- 9.1 Critical severity
- 9.1 Critical severity
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