Linux: Use After Free
CVE-2025-38076 is a high-severity use after free vulnerability in Linux, with a CVSS 3.1 base score of 7.8 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. The record lists versions 3cc733e6d96c938d2b82be96858a0ab900eb6fdc, 12ca42c237756182aad8ab04654c952765cb9061 as the first without the flaw, so updating Linux to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.19% 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 Linux to 3cc733e6d96c938d2b82be96858a0ab900eb6fdc or 12ca42c237756182aad8ab04654c952765cb9061, whichever matches your release line, or a later version.
- Update Linux Kernel to 6.14.9 or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 0db6f8d7820a4b788565dac8eed52bfc2c3216da up to, but not including, 3cc733e6d96c938d2b82be96858a0ab900eb6fdc; 0db6f8d7820a4b788565dac8eed52bfc2c3216da up to, but not including, 12ca42c237756182aad8ab04654c952765cb9061; 6.13 | 3cc733e6d96c938d2b82be96858a0ab900eb6fdc, 12ca42c237756182aad8ab04654c952765cb9061 |
| Linux | Linux Kernel | 6.13 up to, but not including, 6.14.9; 6.15 | 6.14.9 |
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
- UnchangedImpact stays within the vulnerable component.
- 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:L/PR:L/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.
Official description
In the Linux kernel, the following vulnerability has been resolved: alloc_tag: allocate percpu counters for module tags dynamically When a module gets unloaded it checks whether any of its tags are still in use and if so, we keep the memory containing module's allocation tags alive until all tags are unused. However percpu counters referenced by the tags are freed by free_module(). This will lead to UAF if the memory allocated by a module is accessed after module was unloaded. To fix this we allocate percpu counters for module allocation tags dynamically and we keep it alive for tags which are still in use after module unloading. This also removes the requirement of a larger PERCPU_MODULE_RESERVE when memory allocation profiling is enabled because percpu memory for counters does not need to be reserved anymore.
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.
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
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