FreeRTOS-Kernel: Use After Free
CVE-2026-77235 is a high-severity use after free vulnerability in FreeRTOS-Kernel from FreeRTOS, with a CVSS 3.1 base score of 7.3 out of 10. It can be exploited with local access to the system by an attacker with a low-privileged account, without any action from a user. Affected FreeRTOS-Kernel versions: 10.2.0 through 11.3.0. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.16% 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 Freertos to 11.3.1 or a later version.
- Read the advisory on aws.amazon.com for workarounds and exact fixed builds.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| FreeRTOS | FreeRTOS-Kernel | 10.2.0 through 11.3.0 | Not stated |
| Amazon | Freertos | 10.2.0 up to, but not including, 11.3.1 | 11.3.1 |
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
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- LowA basic user account is enough.
- User interaction
- NoneNo action by a victim is required.
- Scope
- ChangedThe attack can reach beyond the vulnerable component into other systems.
- Confidentiality
- NoneNo data is disclosed.
- Integrity
- LowLimited modification of data is possible.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:N/I:L/A:H. Scored by CNA.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 4.0 | 8.3 | High | CNA |
| CVSS 3.1 | 7.3 | High | CNA |
Official description
Missing privilege verification in the secure context cleanup handler in FreeRTOS-Kernel before 11.3.1 might allow local users to cause a use-after-free condition in secure-world memory via the SVC handler for secure context deallocation. To remediate this issue, users should upgrade to version 11.3.1 or later.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Use After Free
The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory belongs to the code that operates on the new pointer.
How developers prevent this class of flaw
- Choose a language that provides automatic memory management.
- When freeing pointers, be sure to set them to NULL once they are freed. However, the utilization of multiple or complex data structures may lower the usefulness of this strategy.
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Advisories
Patches and release notes
Other vulnerabilities in FreeRTOS-Kernel
- 8.8 High severity
- 8.8 High severity
- 8.4 High severity
- 7.3 High severity
- 8.8 High severity
- 7.8 High severity
Recent Use After Free vulnerabilities
- 7.5 High severity
- 8.8 High severity
- 8.8 High severity
- 7.8 High severity
- 7.8 High severity
- 8.4 High severity
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