Linux: Use After Free
CVE-2022-50300 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 b8e7ed42bc3ca0d0e4191ee394d34962d3624c22, fce3713197ebba239e1c7e02174ed216ea1ee014, 169a4cf46882974d4db6d85eb623ec898e51bbc0 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 0.17% 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 b8e7ed42bc3ca0d0e4191ee394d34962d3624c22 or fce3713197ebba239e1c7e02174ed216ea1ee014 or 169a4cf46882974d4db6d85eb623ec898e51bbc0 or 1742e1c90c3da344f3bb9b1f1309b3f47482756a, whichever matches your release line, or a later version.
- Update Linux Kernel to 5.15.87 or 6.0.18 or 6.1.4, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | adfb69af7d8cb6a3958f75aad1ef4bc96891d116 up to, but not including, b8e7ed42bc3ca0d0e4191ee394d34962d3624c22; adfb69af7d8cb6a3958f75aad1ef4bc96891d116 up to, but not including, fce3713197ebba239e1c7e02174ed216ea1ee014; adfb69af7d8cb6a3958f75aad1ef4bc96891d116 up to, but not including, 169a4cf46882974d4db6d85eb623ec898e51bbc0; adfb69af7d8cb6a3958f75aad1ef4bc96891d116 up to, but not including, 1742e1c90c3da344f3bb9b1f1309b3f47482756a; 4.15 | b8e7ed42bc3ca0d0e4191ee394d34962d3624c22, fce3713197ebba239e1c7e02174ed216ea1ee014, 169a4cf46882974d4db6d85eb623ec898e51bbc0, 1742e1c90c3da344f3bb9b1f1309b3f47482756a |
| Linux | Linux Kernel | 4.15 up to, but not including, 5.15.87; 5.16 up to, but not including, 6.0.18; 6.1 up to, but not including, 6.1.4 | 5.15.87, 6.0.18, 6.1.4 |
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: btrfs: fix extent map use-after-free when handling missing device in read_one_chunk Store the error code before freeing the extent_map. Though it's reference counted structure, in that function it's the first and last allocation so this would lead to a potential use-after-free. The error can happen eg. when chunk is stored on a missing device and the degraded mount option is missing. Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=216721
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.
- 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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