Zephyr: Privilege Context Switching Error
CVE-2025-9408 is a high-severity privilege context switching error vulnerability in Zephyr from Zephyrproject-rtos, with a CVSS 3.1 base score of 8.1 out of 10. It can be exploited with local access to the system by an unauthenticated attacker, without any action from a user. The record lists versions 3.7.2, 4.2.2 as the first without the flaw, so updating Zephyr to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.12% 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 Zephyr to 3.7.2 or 4.2.2, whichever matches your release line, or a later version.
- Read the advisory on github.com for workarounds and exact fixed builds.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Zephyrproject-rtos | Zephyr | before 3.7.2; 4.0.0 up to, but not including, 4.2.2 | 3.7.2, 4.2.2 |
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
- NoneNo action by a victim is required.
- 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:N/S:C/C:H/I:H/A:H. Scored by CNA (zephyrproject.org).
Official description
System call entry on Cortex M (and possibly R and A, but I think not) has a race which allows very practical privilege escalation for malicious userspace processes.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Privilege Context Switching Error
The product does not properly manage privileges while it is switching between different contexts that have different privileges or spheres of control.
How developers prevent this class of flaw
- Very carefully manage the setting, management, and handling of privileges. Explicitly manage trust zones in the software.
- Run your code using the lowest privileges that are required to accomplish the necessary tasks. If possible, create isolated accounts with limited privileges that are only used for a single task. That way, a successful attack will not immediately give the attacker access to the rest of the software or its environment. For example, database applications rarely need to run as the database administrator, especially in day-to-day operations.
- Consider following the principle of separation of privilege. Require multiple conditions to be met before permitting access to a system resource.
More Privilege Context Switching Error vulnerabilities (CWE-270)
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 vulnerabilities in Zephyr
- 7.5 High severity
- 8.8 High severity
- 9.8 Critical severity
- 8.8 High severity
- 7.8 High severity
- 7.8 High severity
Recent Privilege Context Switching Error vulnerabilities
- 7.9 High severity
- 8.4 High severity
- 8.8 High severity
- 8.8 High severity
- 8.8 High severity
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