Linux: Use After Free
CVE-2024-40956 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 1b08bf5a17c66ab7dbb628df5344da53c8e7ab33, 83163667d881100a485b6c2daa30301b7f68d9b5, faa35db78b058a2ab6e074ee283f69fa398c36a8 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 1b08bf5a17c66ab7dbb628df5344da53c8e7ab33 or 83163667d881100a485b6c2daa30301b7f68d9b5 or faa35db78b058a2ab6e074ee283f69fa398c36a8 or a14968921486793f2a956086895c3793761309dd, whichever matches your release line, or a later version.
- Update Linux Kernel to 5.15.162 or 6.1.96 or 6.6.36 or 6.9.7, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 16e19e11228ba660d9e322035635e7dcf160d5c2 up to, but not including, 1b08bf5a17c66ab7dbb628df5344da53c8e7ab33; 16e19e11228ba660d9e322035635e7dcf160d5c2 up to, but not including, 83163667d881100a485b6c2daa30301b7f68d9b5; 16e19e11228ba660d9e322035635e7dcf160d5c2 up to, but not including, faa35db78b058a2ab6e074ee283f69fa398c36a8; 16e19e11228ba660d9e322035635e7dcf160d5c2 up to, but not including, a14968921486793f2a956086895c3793761309dd; 16e19e11228ba660d9e322035635e7dcf160d5c2 up to, but not including, e3215deca4520773cd2b155bed164c12365149a7; 5.11 | 1b08bf5a17c66ab7dbb628df5344da53c8e7ab33, 83163667d881100a485b6c2daa30301b7f68d9b5, faa35db78b058a2ab6e074ee283f69fa398c36a8, a14968921486793f2a956086895c3793761309dd, e3215deca4520773cd2b155bed164c12365149a7 |
| Linux | Linux Kernel | 5.11 up to, but not including, 5.15.162; 5.16 up to, but not including, 6.1.96; 6.2 up to, but not including, 6.6.36; 6.7 up to, but not including, 6.9.7; 6.10 | 5.15.162, 6.1.96, 6.6.36, 6.9.7 |
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: dmaengine: idxd: Fix possible Use-After-Free in irq_process_work_list Use list_for_each_entry_safe() to allow iterating through the list and deleting the entry in the iteration process. The descriptor is freed via idxd_desc_complete() and there's a slight chance may cause issue for the list iterator when the descriptor is reused by another thread without it being deleted from the list.
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
- git.kernel.org/stable/c/1b08bf5a17c66ab7dbb628df5344da53c8e7ab33
- git.kernel.org/stable/c/83163667d881100a485b6c2daa30301b7f68d9b5
- git.kernel.org/stable/c/a14968921486793f2a956086895c3793761309dd
- git.kernel.org/stable/c/e3215deca4520773cd2b155bed164c12365149a7
- git.kernel.org/stable/c/faa35db78b058a2ab6e074ee283f69fa398c36a8
Other references
Recent Use After Free vulnerabilities
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