Linux: Use After Free
CVE-2022-50005 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 50403ee6daddf0d7a14e9d3b51a377c39a08ec8c, 9c34c33893db7a80d0e4b55c23d3b65e29609cfb, 2c71f5d55a86fd5969428abf525c1ae6b1c7b0f5 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 0.26% 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 50403ee6daddf0d7a14e9d3b51a377c39a08ec8c or 9c34c33893db7a80d0e4b55c23d3b65e29609cfb or 2c71f5d55a86fd5969428abf525c1ae6b1c7b0f5 or f1e941dbf80a9b8bab0bffbc4cbe41cc7f4c6fb6, whichever matches your release line, or a later version.
- Update Linux Kernel to 5.10.140 or 5.15.64 or 5.19.6, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | c656aa4c27b17a8c70da223ed5ab42145800d6b5 up to, but not including, 50403ee6daddf0d7a14e9d3b51a377c39a08ec8c; c656aa4c27b17a8c70da223ed5ab42145800d6b5 up to, but not including, 9c34c33893db7a80d0e4b55c23d3b65e29609cfb; c656aa4c27b17a8c70da223ed5ab42145800d6b5 up to, but not including, 2c71f5d55a86fd5969428abf525c1ae6b1c7b0f5; c656aa4c27b17a8c70da223ed5ab42145800d6b5 up to, but not including, f1e941dbf80a9b8bab0bffbc4cbe41cc7f4c6fb6; 5.5 | 50403ee6daddf0d7a14e9d3b51a377c39a08ec8c, 9c34c33893db7a80d0e4b55c23d3b65e29609cfb, 2c71f5d55a86fd5969428abf525c1ae6b1c7b0f5, f1e941dbf80a9b8bab0bffbc4cbe41cc7f4c6fb6 |
| Linux | Linux Kernel | 5.5 up to, but not including, 5.10.140; 5.11 up to, but not including, 5.15.64; 5.16 up to, but not including, 5.19.6; 6.0 | 5.10.140, 5.15.64, 5.19.6 |
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.
Official description
In the Linux kernel, the following vulnerability has been resolved: nfc: pn533: Fix use-after-free bugs caused by pn532_cmd_timeout When the pn532 uart device is detaching, the pn532_uart_remove() is called. But there are no functions in pn532_uart_remove() that could delete the cmd_timeout timer, which will cause use-after-free bugs. The process is shown below: (thread 1) | (thread 2) | pn532_uart_send_frame pn532_uart_remove | mod_timer(&pn532->cmd_timeout,...) ... | (wait a time) kfree(pn532) //FREE | pn532_cmd_timeout | pn532_uart_send_frame | pn532->... //USE This patch adds del_timer_sync() in pn532_uart_remove() in order to prevent the use-after-free bugs. What's more, the pn53x_unregister_nfc() is well synchronized, it sets nfc_dev->shutting_down to true and there are no syscalls could restart the cmd_timeout timer.
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
- 8.8 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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