Linux: Use After Free
CVE-2022-49377 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 460aa288c5cd0544dcf933a2f0ad0e8c6d2d35ff, b140bac470b4f707cda59c7266214246238661df, 70fdd922c7bf8949f8df109cf2635dff64c90392 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 0.29% 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 460aa288c5cd0544dcf933a2f0ad0e8c6d2d35ff or b140bac470b4f707cda59c7266214246238661df or 70fdd922c7bf8949f8df109cf2635dff64c90392 or 5d05426e2d5fd7df8afc866b78c36b37b00188b7, whichever matches your release line, or a later version.
- Update Linux Kernel to 5.15.47 or 5.17.15 or 5.18.4, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | b6e68ee82585f2ee890b0a897a6aacbf49a467bb up to, but not including, 460aa288c5cd0544dcf933a2f0ad0e8c6d2d35ff; b6e68ee82585f2ee890b0a897a6aacbf49a467bb up to, but not including, b140bac470b4f707cda59c7266214246238661df; b6e68ee82585f2ee890b0a897a6aacbf49a467bb up to, but not including, 70fdd922c7bf8949f8df109cf2635dff64c90392; b6e68ee82585f2ee890b0a897a6aacbf49a467bb up to, but not including, 5d05426e2d5fd7df8afc866b78c36b37b00188b7; 5.12 | 460aa288c5cd0544dcf933a2f0ad0e8c6d2d35ff, b140bac470b4f707cda59c7266214246238661df, 70fdd922c7bf8949f8df109cf2635dff64c90392, 5d05426e2d5fd7df8afc866b78c36b37b00188b7 |
| Linux | Linux Kernel | 5.12 up to, but not including, 5.15.47; 5.16 up to, but not including, 5.17.15; 5.18 up to, but not including, 5.18.4 | 5.15.47, 5.17.15, 5.18.4 |
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 CISA (ADP).
Official description
In the Linux kernel, the following vulnerability has been resolved: blk-mq: don't touch ->tagset in blk_mq_get_sq_hctx blk_mq_run_hw_queues() could be run when there isn't queued request and after queue is cleaned up, at that time tagset is freed, because tagset lifetime is covered by driver, and often freed after blk_cleanup_queue() returns. So don't touch ->tagset for figuring out current default hctx by the mapping built in request queue, so use-after-free on tagset can be avoided. Meantime this way should be fast than retrieving mapping from tagset.
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
Spotted an error? Tell us.