Linux: Use After Free
CVE-2022-48637 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 08483e4c0c83b221b8891434a04cec405dee94a6, 32afa1f23e42cc635ccf4c39f24514d03d1e8338, c31f26c8f69f776759cbbdfb38e40ea91aa0dd65 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 08483e4c0c83b221b8891434a04cec405dee94a6 or 32afa1f23e42cc635ccf4c39f24514d03d1e8338 or c31f26c8f69f776759cbbdfb38e40ea91aa0dd65, whichever matches your release line, or a later version.
- Update Linux Kernel to 5.15.71 or 5.19.12, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 83bb623c968e7351aee5111547693f95f330dc5a up to, but not including, 08483e4c0c83b221b8891434a04cec405dee94a6; 83bb623c968e7351aee5111547693f95f330dc5a up to, but not including, 32afa1f23e42cc635ccf4c39f24514d03d1e8338; 83bb623c968e7351aee5111547693f95f330dc5a up to, but not including, c31f26c8f69f776759cbbdfb38e40ea91aa0dd65; 5.14 | 08483e4c0c83b221b8891434a04cec405dee94a6, 32afa1f23e42cc635ccf4c39f24514d03d1e8338, c31f26c8f69f776759cbbdfb38e40ea91aa0dd65 |
| Linux | Linux Kernel | 5.14 up to, but not including, 5.15.71; 5.16 up to, but not including, 5.19.12; 6.0 | 5.15.71, 5.19.12 |
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: bnxt: prevent skb UAF after handing over to PTP worker When reading the timestamp is required bnxt_tx_int() hands over the ownership of the completed skb to the PTP worker. The skb should not be used afterwards, as the worker may run before the rest of our code and free the skb, leading to a use-after-free. Since dev_kfree_skb_any() accepts NULL make the loss of ownership more obvious and set skb to NULL.
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
- 9.8 Critical severity
- 7.8 High severity
- 8.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
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