Linux: Use After Free
CVE-2022-49136 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 1c69ef84a808676cceb69210addf5df45b741323, 0b94f2651f56b9e4aa5f012b0d7eb57308c773cf 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 1c69ef84a808676cceb69210addf5df45b741323 or 0b94f2651f56b9e4aa5f012b0d7eb57308c773cf, whichever matches your release line, or a later version.
- Update Linux Kernel to 5.17.3 or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 6a98e3836fa2077b169f10a35c2ca9952d53f987 up to, but not including, 1c69ef84a808676cceb69210addf5df45b741323; 6a98e3836fa2077b169f10a35c2ca9952d53f987 up to, but not including, 0b94f2651f56b9e4aa5f012b0d7eb57308c773cf; 5.17 | 1c69ef84a808676cceb69210addf5df45b741323, 0b94f2651f56b9e4aa5f012b0d7eb57308c773cf |
| Linux | Linux Kernel | 5.17 up to, but not including, 5.17.3 | 5.17.3 |
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: Bluetooth: hci_sync: Fix queuing commands when HCI_UNREGISTER is set hci_cmd_sync_queue shall return an error if HCI_UNREGISTER flag has been set as that means hci_unregister_dev has been called so it will likely cause a uaf after the timeout as the hdev will be freed.
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
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- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
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