Linux: Use After Free
CVE-2022-48873 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 4b5c44e924a571d0ad07054de549624fbc04e4d7, 193cd853145b63e670bd73740250983af1475330, 1b7b7bb400dd13dcb03fc6e591bb7ca4664bbec8 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 0.24% 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 4b5c44e924a571d0ad07054de549624fbc04e4d7 or 193cd853145b63e670bd73740250983af1475330 or 1b7b7bb400dd13dcb03fc6e591bb7ca4664bbec8 or 35ddd482345c43d9eec1f3406c0f20a95ed4054b, whichever matches your release line, or a later version.
- Update Linux Kernel to 5.4.230 or 5.10.165 or 5.15.90 or 6.1.8, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | b49f6d83e290f17e20f4e5cf31288d3bb4955ea6 up to, but not including, 4b5c44e924a571d0ad07054de549624fbc04e4d7; b49f6d83e290f17e20f4e5cf31288d3bb4955ea6 up to, but not including, 193cd853145b63e670bd73740250983af1475330; b49f6d83e290f17e20f4e5cf31288d3bb4955ea6 up to, but not including, 1b7b7bb400dd13dcb03fc6e591bb7ca4664bbec8; b49f6d83e290f17e20f4e5cf31288d3bb4955ea6 up to, but not including, 35ddd482345c43d9eec1f3406c0f20a95ed4054b; b49f6d83e290f17e20f4e5cf31288d3bb4955ea6 up to, but not including, 5bb96c8f9268e2fdb0e5321cbc358ee5941efc15; aaf5aa44934ad069cac805923c49f6968b9a0d49; 5.1.6 up to, but not including, 5.2; 5.2 | 4b5c44e924a571d0ad07054de549624fbc04e4d7, 193cd853145b63e670bd73740250983af1475330, 1b7b7bb400dd13dcb03fc6e591bb7ca4664bbec8, 35ddd482345c43d9eec1f3406c0f20a95ed4054b, 5bb96c8f9268e2fdb0e5321cbc358ee5941efc15, 5.2 |
| Linux | Linux Kernel | 5.2 up to, but not including, 5.4.230; 5.5 up to, but not including, 5.10.165; 5.11 up to, but not including, 5.15.90; 5.16 up to, but not including, 6.1.8; 6.2 | 5.4.230, 5.10.165, 5.15.90, 6.1.8 |
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: misc: fastrpc: Don't remove map on creater_process and device_release Do not remove the map from the list on error path in fastrpc_init_create_process, instead call fastrpc_map_put, to avoid use-after-free. Do not remove it on fastrpc_device_release either, call fastrpc_map_put instead. The fastrpc_free_map is the only proper place to remove the map. This is called only after the reference count is 0.
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
- git.kernel.org/stable/c/193cd853145b63e670bd73740250983af1475330
- git.kernel.org/stable/c/1b7b7bb400dd13dcb03fc6e591bb7ca4664bbec8
- git.kernel.org/stable/c/35ddd482345c43d9eec1f3406c0f20a95ed4054b
- git.kernel.org/stable/c/4b5c44e924a571d0ad07054de549624fbc04e4d7
- git.kernel.org/stable/c/5bb96c8f9268e2fdb0e5321cbc358ee5941efc15
Recent Use After Free vulnerabilities
- 8.8 High severity
- 8.8 High severity
- 8.8 High severity
- 8.8 High severity
- 8.8 High severity
- 7.8 High severity
Spotted an error? Tell us.