Linux: Use After Free
CVE-2022-49711 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 720ab105df7bf3eee62d2bddd41526b29d07d045, ccd1751092341ac120a961835211f9f2e3735963, 161b68b0a728377aaa10a8e14c70e7734f3c9ff7 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 720ab105df7bf3eee62d2bddd41526b29d07d045 or ccd1751092341ac120a961835211f9f2e3735963 or 161b68b0a728377aaa10a8e14c70e7734f3c9ff7 or 928ea98252ad75118950941683893cf904541da9, whichever matches your release line, or a later version.
- Update Linux Kernel to 5.10.248 or 5.15.49 or 5.18.6, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | f93627146f0e371093966ed3d44c065aa077cfb1 up to, but not including, 720ab105df7bf3eee62d2bddd41526b29d07d045; f93627146f0e371093966ed3d44c065aa077cfb1 up to, but not including, ccd1751092341ac120a961835211f9f2e3735963; f93627146f0e371093966ed3d44c065aa077cfb1 up to, but not including, 161b68b0a728377aaa10a8e14c70e7734f3c9ff7; f93627146f0e371093966ed3d44c065aa077cfb1 up to, but not including, 928ea98252ad75118950941683893cf904541da9; 4.8 | 720ab105df7bf3eee62d2bddd41526b29d07d045, ccd1751092341ac120a961835211f9f2e3735963, 161b68b0a728377aaa10a8e14c70e7734f3c9ff7, 928ea98252ad75118950941683893cf904541da9 |
| Linux | Linux Kernel | 4.8 up to, but not including, 5.10.248; 5.11 up to, but not including, 5.15.49; 5.16 up to, but not including, 5.18.6; 5.19 | 5.10.248, 5.15.49, 5.18.6 |
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 CISA (ADP).
Official description
In the Linux kernel, the following vulnerability has been resolved: bus: fsl-mc-bus: fix KASAN use-after-free in fsl_mc_bus_remove() In fsl_mc_bus_remove(), mc->root_mc_bus_dev->mc_io is passed to fsl_destroy_mc_io(). However, mc->root_mc_bus_dev is already freed in fsl_mc_device_remove(). Then reference to mc->root_mc_bus_dev->mc_io triggers KASAN use-after-free. To avoid the use-after-free, keep the reference to mc->root_mc_bus_dev->mc_io in a local variable and pass to fsl_destroy_mc_io(). This patch needs rework to apply to kernels older than v5.15.
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: total).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
Recent Use After Free vulnerabilities
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
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