Linux: Use After Free
CVE-2025-37849 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 07476e0d932afc53c05468076393ac35d0b4999e, 5085e02362b9948f82fceca979b8f8e12acb1cc5, c322789613407647a05ff5c451a7bf545fb34e73 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 0.27% 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 07476e0d932afc53c05468076393ac35d0b4999e or 5085e02362b9948f82fceca979b8f8e12acb1cc5 or c322789613407647a05ff5c451a7bf545fb34e73 or 2480326eba8ae9ccc5e4c3c2dc8d407db68e3c52, whichever matches your release line, or a later version.
- Update Linux Kernel to 6.1.135 or 6.6.88 or 6.12.24 or 6.13.12, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 6211753fdfd05af9e08f54c8d0ba3ee516034878 up to, but not including, 07476e0d932afc53c05468076393ac35d0b4999e; 6211753fdfd05af9e08f54c8d0ba3ee516034878 up to, but not including, 5085e02362b9948f82fceca979b8f8e12acb1cc5; 6211753fdfd05af9e08f54c8d0ba3ee516034878 up to, but not including, c322789613407647a05ff5c451a7bf545fb34e73; 6211753fdfd05af9e08f54c8d0ba3ee516034878 up to, but not including, 2480326eba8ae9ccc5e4c3c2dc8d407db68e3c52; 6211753fdfd05af9e08f54c8d0ba3ee516034878 up to, but not including, f1e9087abaeedec9bf2894a282ee4f0d8383f299; 6211753fdfd05af9e08f54c8d0ba3ee516034878 up to, but not including, 250f25367b58d8c65a1b060a2dda037eea09a672; 3.11 | 07476e0d932afc53c05468076393ac35d0b4999e, 5085e02362b9948f82fceca979b8f8e12acb1cc5, c322789613407647a05ff5c451a7bf545fb34e73, 2480326eba8ae9ccc5e4c3c2dc8d407db68e3c52, f1e9087abaeedec9bf2894a282ee4f0d8383f299, 250f25367b58d8c65a1b060a2dda037eea09a672 |
| Linux | Linux Kernel | before 6.1.135; 6.2 up to, but not including, 6.6.88; 6.7 up to, but not including, 6.12.24; 6.13 up to, but not including, 6.13.12; 6.14 up to, but not including, 6.14.3 | 6.1.135, 6.6.88, 6.12.24, 6.13.12, 6.14.3 |
| Debian | Debian Linux | 11.0 | Not stated |
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.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 8.8 | High | CNA |
| CVSS 3.1 | 7.8 | High | NVD |
Official description
In the Linux kernel, the following vulnerability has been resolved: KVM: arm64: Tear down vGIC on failed vCPU creation If kvm_arch_vcpu_create() fails to share the vCPU page with the hypervisor, we propagate the error back to the ioctl but leave the vGIC vCPU data initialised. Note only does this leak the corresponding memory when the vCPU is destroyed but it can also lead to use-after-free if the redistributor device handling tries to walk into the vCPU. Add the missing cleanup to kvm_arch_vcpu_create(), ensuring that the vGIC vCPU structures are destroyed on error.
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
- git.kernel.org/stable/c/07476e0d932afc53c05468076393ac35d0b4999e
- git.kernel.org/stable/c/2480326eba8ae9ccc5e4c3c2dc8d407db68e3c52
- git.kernel.org/stable/c/250f25367b58d8c65a1b060a2dda037eea09a672
- git.kernel.org/stable/c/5085e02362b9948f82fceca979b8f8e12acb1cc5
- git.kernel.org/stable/c/c322789613407647a05ff5c451a7bf545fb34e73
- git.kernel.org/stable/c/f1e9087abaeedec9bf2894a282ee4f0d8383f299
Other references
Recent Use After Free vulnerabilities
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