Linux: Use After Free
CVE-2022-49419 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 0fac5f8fb1bc2fc4f8714bf5e743c9cc3f547c63, f605f5558ecc175ec70016a3c15f007cb6386531, d260cad015945d1f4bb9b028a096f648506106a2 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 0fac5f8fb1bc2fc4f8714bf5e743c9cc3f547c63 or f605f5558ecc175ec70016a3c15f007cb6386531 or d260cad015945d1f4bb9b028a096f648506106a2 or acde4003efc16480375543638484d8f13f2e99a3, whichever matches your release line, or a later version.
- Update Linux Kernel to 5.15.46 or 5.17.14 or 5.18.3, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | f94aa46efaa087ec075c83e4508f943fb5e43977 up to, but not including, 0fac5f8fb1bc2fc4f8714bf5e743c9cc3f547c63; a1aac13288de2935dc1a9330a93b1ac92f1e2b72 up to, but not including, f605f5558ecc175ec70016a3c15f007cb6386531; b3c9a924aab61adbc29df110006aa03afe1a78ba up to, but not including, d260cad015945d1f4bb9b028a096f648506106a2; b3c9a924aab61adbc29df110006aa03afe1a78ba up to, but not including, acde4003efc16480375543638484d8f13f2e99a3; 5.15.41 up to, but not including, 5.15.46; 5.17.9 up to, but not including, 5.17.14; 5.18 | 0fac5f8fb1bc2fc4f8714bf5e743c9cc3f547c63, f605f5558ecc175ec70016a3c15f007cb6386531, d260cad015945d1f4bb9b028a096f648506106a2, acde4003efc16480375543638484d8f13f2e99a3, 5.15.46, 5.17.14 |
| Linux | Linux Kernel | 5.15.41 up to, but not including, 5.15.46; 5.17.9 up to, but not including, 5.17.14; 5.18 up to, but not including, 5.18.3 | 5.15.46, 5.17.14, 5.18.3 |
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: video: fbdev: vesafb: Fix a use-after-free due early fb_info cleanup Commit b3c9a924aab6 ("fbdev: vesafb: Cleanup fb_info in .fb_destroy rather than .remove") fixed a use-after-free error due the vesafb driver freeing the fb_info in the .remove handler instead of doing it in .fb_destroy. This can happen if the .fb_destroy callback is executed after the .remove callback, since the former tries to access a pointer freed by the latter. But that change didn't take into account that another possible scenario is that .fb_destroy is called before the .remove callback. For example, if no process has the fbdev chardev opened by the time the driver is removed. If that's the case, fb_info will be freed when unregister_framebuffer() is called, making the fb_info pointer accessed in vesafb_remove() after that to no longer be valid. To prevent that, move the expression containing the info->par to happen before the unregister_framebuffer() function call.
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
- 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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