Linux: Use After Free
CVE-2022-49258 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 c93017c8d5ebf55a4e453ac7c84cc84cf92ab570, 335bf1fc74f775a8255257aa3e33763f2257b676, 25c358efee5153dfd240d4e0d3169d5bebe9cacd 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 c93017c8d5ebf55a4e453ac7c84cc84cf92ab570 or 335bf1fc74f775a8255257aa3e33763f2257b676 or 25c358efee5153dfd240d4e0d3169d5bebe9cacd or cffb5382bd8d3cf21b874ab5b84bf7618932286b, whichever matches your release line, or a later version.
- Update Linux Kernel to 5.10.110 or 5.15.33 or 5.16.19 or 5.17.2, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 63ee04c8b491ee148489347e7da9fbfd982ca2bb up to, but not including, c93017c8d5ebf55a4e453ac7c84cc84cf92ab570; 63ee04c8b491ee148489347e7da9fbfd982ca2bb up to, but not including, 335bf1fc74f775a8255257aa3e33763f2257b676; 63ee04c8b491ee148489347e7da9fbfd982ca2bb up to, but not including, 25c358efee5153dfd240d4e0d3169d5bebe9cacd; 63ee04c8b491ee148489347e7da9fbfd982ca2bb up to, but not including, cffb5382bd8d3cf21b874ab5b84bf7618932286b; 63ee04c8b491ee148489347e7da9fbfd982ca2bb up to, but not including, 3d950c34074ed74d2713c3856ba01264523289e6; 4.17 | c93017c8d5ebf55a4e453ac7c84cc84cf92ab570, 335bf1fc74f775a8255257aa3e33763f2257b676, 25c358efee5153dfd240d4e0d3169d5bebe9cacd, cffb5382bd8d3cf21b874ab5b84bf7618932286b, 3d950c34074ed74d2713c3856ba01264523289e6 |
| Linux | Linux Kernel | 4.17 up to, but not including, 5.10.110; 5.11 up to, but not including, 5.15.33; 5.16 up to, but not including, 5.16.19; 5.17 up to, but not including, 5.17.2 | 5.10.110, 5.15.33, 5.16.19, 5.17.2 |
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: crypto: ccree - Fix use after free in cc_cipher_exit() kfree_sensitive(ctx_p->user.key) will free the ctx_p->user.key. But ctx_p->user.key is still used in the next line, which will lead to a use after free. We can call kfree_sensitive() after dev_dbg() to avoid the uaf.
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
- git.kernel.org/stable/c/25c358efee5153dfd240d4e0d3169d5bebe9cacd
- git.kernel.org/stable/c/335bf1fc74f775a8255257aa3e33763f2257b676
- git.kernel.org/stable/c/3d950c34074ed74d2713c3856ba01264523289e6
- git.kernel.org/stable/c/c93017c8d5ebf55a4e453ac7c84cc84cf92ab570
- git.kernel.org/stable/c/cffb5382bd8d3cf21b874ab5b84bf7618932286b
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
Spotted an error? Tell us.