Linux: Use After Free
CVE-2022-48735 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 a7de1002135cf94367748ffc695a29812d7633b5, 0e629052f013eeb61494d4df2f1f647c2a9aef47, 813e9f3e06d22e29872d4fd51b54992d89cf66c8 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 0.23% 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 a7de1002135cf94367748ffc695a29812d7633b5 or 0e629052f013eeb61494d4df2f1f647c2a9aef47 or 813e9f3e06d22e29872d4fd51b54992d89cf66c8 or 549f8ffc7b2f7561bea7f90930b6c5104318e87b, whichever matches your release line, or a later version.
- Update Linux Kernel to 5.10.99 or 5.15.22 or 5.16.8, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 15509b6344726de22bdbfff88b65341dd0dd33af up to, but not including, a7de1002135cf94367748ffc695a29812d7633b5; 15509b6344726de22bdbfff88b65341dd0dd33af up to, but not including, 0e629052f013eeb61494d4df2f1f647c2a9aef47; 15509b6344726de22bdbfff88b65341dd0dd33af up to, but not including, 813e9f3e06d22e29872d4fd51b54992d89cf66c8; 15509b6344726de22bdbfff88b65341dd0dd33af up to, but not including, 549f8ffc7b2f7561bea7f90930b6c5104318e87b; 5.9 | a7de1002135cf94367748ffc695a29812d7633b5, 0e629052f013eeb61494d4df2f1f647c2a9aef47, 813e9f3e06d22e29872d4fd51b54992d89cf66c8, 549f8ffc7b2f7561bea7f90930b6c5104318e87b |
| Linux | Linux Kernel | 5.9 up to, but not including, 5.10.99; 5.11 up to, but not including, 5.15.22; 5.16 up to, but not including, 5.16.8; 5.17 | 5.10.99, 5.15.22, 5.16.8 |
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.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 7.8 | High | CNA |
| CVSS 3.1 | 7.8 | High | NVD |
Official description
In the Linux kernel, the following vulnerability has been resolved: ALSA: hda: Fix UAF of leds class devs at unbinding The LED class devices that are created by HD-audio codec drivers are registered via devm_led_classdev_register() and associated with the HD-audio codec device. Unfortunately, it turned out that the devres release doesn't work for this case; namely, since the codec resource release happens before the devm call chain, it triggers a NULL dereference or a UAF for a stale set_brightness_delay callback. For fixing the bug, this patch changes the LED class device register and unregister in a manual manner without devres, keeping the instances in hda_gen_spec.
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: partial).
- 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
- 8.8 High severity
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