Linux: Use After Free
CVE-2022-49026 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 b775f37d943966f6f77dca402f5a9dedce502c25, 9fc27d22cdb9b1fcd754599d216a8992fed280cd, b46f6144ab89d3d757ead940759c505091626a7d 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 0.24% 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 b775f37d943966f6f77dca402f5a9dedce502c25 or 9fc27d22cdb9b1fcd754599d216a8992fed280cd or b46f6144ab89d3d757ead940759c505091626a7d or 45605c75c52c7ae7bfe902214343aabcfe5ba0ff, whichever matches your release line, or a later version.
- Update Linux Kernel to 5.10.158 or 5.15.82 or 6.0.12, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 5e5d49422dfb035ca9e280cd61d434095c151272 up to, but not including, b775f37d943966f6f77dca402f5a9dedce502c25; 5e5d49422dfb035ca9e280cd61d434095c151272 up to, but not including, 9fc27d22cdb9b1fcd754599d216a8992fed280cd; 5e5d49422dfb035ca9e280cd61d434095c151272 up to, but not including, b46f6144ab89d3d757ead940759c505091626a7d; 5e5d49422dfb035ca9e280cd61d434095c151272 up to, but not including, 45605c75c52c7ae7bfe902214343aabcfe5ba0ff; 4.3 | b775f37d943966f6f77dca402f5a9dedce502c25, 9fc27d22cdb9b1fcd754599d216a8992fed280cd, b46f6144ab89d3d757ead940759c505091626a7d, 45605c75c52c7ae7bfe902214343aabcfe5ba0ff |
| Linux | Linux Kernel | 4.3 up to, but not including, 5.10.158; 5.11 up to, but not including, 5.15.82; 5.16 up to, but not including, 6.0.12; 6.1 | 5.10.158, 5.15.82, 6.0.12 |
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 NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 7.8 | High | CNA |
| CVSS 3.1 | 7.8 | High | NVD |
Official description
In the Linux kernel, the following vulnerability has been resolved: e100: Fix possible use after free in e100_xmit_prepare In e100_xmit_prepare(), if we can't map the skb, then return -ENOMEM, so e100_xmit_frame() will return NETDEV_TX_BUSY and the upper layer will resend the skb. But the skb is already freed, which will cause UAF bug when the upper layer resends the skb. Remove the harmful free.
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: partial).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
Recent Use After Free vulnerabilities
- 7.0 High severity
- 7.0 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
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