Linux: Use After Free
CVE-2022-49493 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 236d29c5857f02e0a53fdf15d3dce1536c4322ce, 0941150100173d4eaf3fe08ff4b16740e7c3026f, abe7554da62cb489712a54de69ef5665c250e564 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 236d29c5857f02e0a53fdf15d3dce1536c4322ce or 0941150100173d4eaf3fe08ff4b16740e7c3026f or abe7554da62cb489712a54de69ef5665c250e564 or 1a5a3dfd9f172dcb115072f0aea5e27d3083c20e, whichever matches your release line, or a later version.
- Update Linux Kernel to 4.9.318 or 4.14.283 or 4.19.247 or 5.4.198, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | a6ff8ddcf3f38ec84337e5e7eb3e0e9a73754cf5 up to, but not including, 236d29c5857f02e0a53fdf15d3dce1536c4322ce; a6ff8ddcf3f38ec84337e5e7eb3e0e9a73754cf5 up to, but not including, 0941150100173d4eaf3fe08ff4b16740e7c3026f; a6ff8ddcf3f38ec84337e5e7eb3e0e9a73754cf5 up to, but not including, abe7554da62cb489712a54de69ef5665c250e564; a6ff8ddcf3f38ec84337e5e7eb3e0e9a73754cf5 up to, but not including, 1a5a3dfd9f172dcb115072f0aea5e27d3083c20e; a6ff8ddcf3f38ec84337e5e7eb3e0e9a73754cf5 up to, but not including, 061a6159cea583f1155f67d1915917a6b9282662; a6ff8ddcf3f38ec84337e5e7eb3e0e9a73754cf5 up to, but not including, 88c09e4812d72c3153afc8e5a45ecac2d0eae3ff; a6ff8ddcf3f38ec84337e5e7eb3e0e9a73754cf5 up to, but not including, 453f0920ffc1a28e28ddb9c3cd5562472b2895b0; a6ff8ddcf3f38ec84337e5e7eb3e0e9a73754cf5 up to, but not including, 2def44d3aec59e38d2701c568d65540783f90f2f; and 1 more ranges | 236d29c5857f02e0a53fdf15d3dce1536c4322ce, 0941150100173d4eaf3fe08ff4b16740e7c3026f, abe7554da62cb489712a54de69ef5665c250e564, 1a5a3dfd9f172dcb115072f0aea5e27d3083c20e, 061a6159cea583f1155f67d1915917a6b9282662, 88c09e4812d72c3153afc8e5a45ecac2d0eae3ff |
| Linux | Linux Kernel | before 4.9.318; 4.10 up to, but not including, 4.14.283; 4.15 up to, but not including, 4.19.247; 4.20 up to, but not including, 5.4.198; 5.5 up to, but not including, 5.10.121; 5.11 up to, but not including, 5.15.46; 5.16 up to, but not including, 5.17.14; 5.18 up to, but not including, 5.18.3 | 4.9.318, 4.14.283, 4.19.247, 5.4.198, 5.10.121, 5.15.46 |
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: ASoC: rt5645: Fix errorenous cleanup order There is a logic error when removing rt5645 device as the function rt5645_i2c_remove() first cancel the &rt5645->jack_detect_work and delete the &rt5645->btn_check_timer latter. However, since the timer handler rt5645_btn_check_callback() will re-queue the jack_detect_work, this cleanup order is buggy. That is, once the del_timer_sync in rt5645_i2c_remove is concurrently run with the rt5645_btn_check_callback, the canceled jack_detect_work will be rescheduled again, leading to possible use-after-free. This patch fix the issue by placing the del_timer_sync function before the cancel_delayed_work_sync.
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/061a6159cea583f1155f67d1915917a6b9282662
- git.kernel.org/stable/c/0941150100173d4eaf3fe08ff4b16740e7c3026f
- git.kernel.org/stable/c/1a5a3dfd9f172dcb115072f0aea5e27d3083c20e
- git.kernel.org/stable/c/236d29c5857f02e0a53fdf15d3dce1536c4322ce
- git.kernel.org/stable/c/2def44d3aec59e38d2701c568d65540783f90f2f
- git.kernel.org/stable/c/453f0920ffc1a28e28ddb9c3cd5562472b2895b0
- git.kernel.org/stable/c/88c09e4812d72c3153afc8e5a45ecac2d0eae3ff
- git.kernel.org/stable/c/abe7554da62cb489712a54de69ef5665c250e564
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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