Linux: Use After Free
CVE-2022-49622 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 348218a4601e93de4d1e9fab29837cf656e4bf99, 453a67af8bd77463b33cb0336dd7f2341e332d29, 0016d5d46d7440729a3132f61a8da3bf7f84e2ba 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 348218a4601e93de4d1e9fab29837cf656e4bf99 or 453a67af8bd77463b33cb0336dd7f2341e332d29 or 0016d5d46d7440729a3132f61a8da3bf7f84e2ba or e34b9ed96ce3b06c79bf884009b16961ca478f87, whichever matches your release line, or a later version.
- Update Linux Kernel to 5.18.13 or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 5efa0fc6d7f7930b18801f07cefae8eeacd6ac02 up to, but not including, 348218a4601e93de4d1e9fab29837cf656e4bf99; 5efa0fc6d7f7930b18801f07cefae8eeacd6ac02 up to, but not including, 453a67af8bd77463b33cb0336dd7f2341e332d29; 5efa0fc6d7f7930b18801f07cefae8eeacd6ac02 up to, but not including, 0016d5d46d7440729a3132f61a8da3bf7f84e2ba; 5efa0fc6d7f7930b18801f07cefae8eeacd6ac02 up to, but not including, e34b9ed96ce3b06c79bf884009b16961ca478f87; 4.10 | 348218a4601e93de4d1e9fab29837cf656e4bf99, 453a67af8bd77463b33cb0336dd7f2341e332d29, 0016d5d46d7440729a3132f61a8da3bf7f84e2ba, e34b9ed96ce3b06c79bf884009b16961ca478f87 |
| Linux | Linux Kernel | before 5.18.13; 5.19 | 5.18.13 |
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 CNA.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 7.8 | High | CNA |
| CVSS 3.1 | 7.8 | High | CISA (ADP) |
Official description
In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_tables: avoid skb access on nf_stolen When verdict is NF_STOLEN, the skb might have been freed. When tracing is enabled, this can result in a use-after-free: 1. access to skb->nf_trace 2. access to skb->mark 3. computation of trace id 4. dump of packet payload To avoid 1, keep a cached copy of skb->nf_trace in the trace state struct. Refresh this copy whenever verdict is != STOLEN. Avoid 2 by skipping skb->mark access if verdict is STOLEN. 3 is avoided by precomputing the trace id. Only dump the packet when verdict is not "STOLEN".
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
Other references
Recent Use After Free vulnerabilities
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- 7.8 High severity
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