Linux: Use After Free
CVE-2022-49651 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 e997dda6502eefbc1032d6b0da7b353c53344b07, 8ed00760203d8018bee042fbfe8e076579be2c2b 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 e997dda6502eefbc1032d6b0da7b353c53344b07 or 8ed00760203d8018bee042fbfe8e076579be2c2b, whichever matches your release line, or a later version.
- Update Linux Kernel to 5.18.11 or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | da915ad5cf25b5f5d358dd3670c3378d8ae8c03e up to, but not including, e997dda6502eefbc1032d6b0da7b353c53344b07; da915ad5cf25b5f5d358dd3670c3378d8ae8c03e up to, but not including, 8ed00760203d8018bee042fbfe8e076579be2c2b; 4.12 | e997dda6502eefbc1032d6b0da7b353c53344b07, 8ed00760203d8018bee042fbfe8e076579be2c2b |
| Linux | Linux Kernel | before 5.18.11 | 5.18.11 |
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: srcu: Tighten cleanup_srcu_struct() GP checks Currently, cleanup_srcu_struct() checks for a grace period in progress, but it does not check for a grace period that has not yet started but which might start at any time. Such a situation could result in a use-after-free bug, so this commit adds a check for a grace period that is needed but not yet started to cleanup_srcu_struct().
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.