Linux: Use After Free
CVE-2022-49362 is a critical-severity use after free vulnerability in Linux, with a CVSS 3.1 base score of 9.8 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists versions ada1757b259f353cade47037ee0a0249b4cddad3, 261eabe19cb28e4a8587a4442d257b543d7c2d57, 333dcc94ebf53f79f3dc0e7a7c16700bc7ff7e57 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 0.65% chance of exploitation within 30 days, higher than 52% of scored CVEs.
Critical severity: a successful attack would have severe impact.
What to do
- Update Linux to ada1757b259f353cade47037ee0a0249b4cddad3 or 261eabe19cb28e4a8587a4442d257b543d7c2d57 or 333dcc94ebf53f79f3dc0e7a7c16700bc7ff7e57 or b6c71c66b0ad8f2b59d9bc08c7a5079b110bec01, whichever matches your release line, or a later version.
- Update Linux Kernel to 5.18.4 or a later version.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 9862064ca81f9b9da8ebe26c86cf2b10c293ba1a up to, but not including, ada1757b259f353cade47037ee0a0249b4cddad3; a98e5b3d958ac697aafb3d077eb2cca4a731b7ee up to, but not including, 261eabe19cb28e4a8587a4442d257b543d7c2d57; 999397926ab3f78c7d1235cc4ca6e3c89d2769bf up to, but not including, 333dcc94ebf53f79f3dc0e7a7c16700bc7ff7e57; 999397926ab3f78c7d1235cc4ca6e3c89d2769bf up to, but not including, b6c71c66b0ad8f2b59d9bc08c7a5079b110bec01; 5.18 | ada1757b259f353cade47037ee0a0249b4cddad3, 261eabe19cb28e4a8587a4442d257b543d7c2d57, 333dcc94ebf53f79f3dc0e7a7c16700bc7ff7e57, b6c71c66b0ad8f2b59d9bc08c7a5079b110bec01 |
| Linux | Linux Kernel | 5.18 up to, but not including, 5.18.4; 5.19 | 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
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- 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:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H. Scored by CNA.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 9.8 | Critical | CNA |
| CVSS 3.1 | 7.8 | High | CISA (ADP) |
Official description
In the Linux kernel, the following vulnerability has been resolved: NFSD: Fix potential use-after-free in nfsd_file_put() nfsd_file_put_noref() can free @nf, so don't dereference @nf immediately upon return from nfsd_file_put_noref().
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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