Linux: Use After Free
CVE-2022-49951 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 d380d40930a674c520a5b55f3be1eb17dc634ebc, 8b40c38e37492b5bdf8e95b46b5cca9517a9957a 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 0.26% 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 d380d40930a674c520a5b55f3be1eb17dc634ebc or 8b40c38e37492b5bdf8e95b46b5cca9517a9957a, whichever matches your release line, or a later version.
- Update Linux Kernel to 5.19.8 or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 97730bbb242cde22b7140acd202ffd88823886c9 up to, but not including, d380d40930a674c520a5b55f3be1eb17dc634ebc; 97730bbb242cde22b7140acd202ffd88823886c9 up to, but not including, 8b40c38e37492b5bdf8e95b46b5cca9517a9957a; 5.19 | d380d40930a674c520a5b55f3be1eb17dc634ebc, 8b40c38e37492b5bdf8e95b46b5cca9517a9957a |
| Linux | Linux Kernel | 5.19 up to, but not including, 5.19.8; 6.0 | 5.19.8 |
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: firmware_loader: Fix use-after-free during unregister In the following code within firmware_upload_unregister(), the call to device_unregister() could result in the dev_release function freeing the fw_upload_priv structure before it is dereferenced for the call to module_put(). This bug was found by the kernel test robot using CONFIG_KASAN while running the firmware selftests. device_unregister(&fw_sysfs->dev); module_put(fw_upload_priv->module); The problem is fixed by copying fw_upload_priv->module to a local variable for use when calling device_unregister().
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
Recent Use After Free vulnerabilities
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