Linux: Use After Free
CVE-2023-52445 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 ec36c134dd020d28e312c2f1766f85525e747aab, 47aa8fcd5e8b5563af4042a00f25ba89bef8f33d, 3233d8bf7893550045682192cb227af7fa3defeb 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 ec36c134dd020d28e312c2f1766f85525e747aab or 47aa8fcd5e8b5563af4042a00f25ba89bef8f33d or 3233d8bf7893550045682192cb227af7fa3defeb or ec3634ebe23fc3c44ebc67c6d25917300bc68c08, whichever matches your release line, or a later version.
- Update Linux Kernel to 4.19.306 or 5.4.268 or 5.10.209 or 5.15.148, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | e5be15c63804e05b5a94197524023702a259e308 up to, but not including, ec36c134dd020d28e312c2f1766f85525e747aab; e5be15c63804e05b5a94197524023702a259e308 up to, but not including, 47aa8fcd5e8b5563af4042a00f25ba89bef8f33d; e5be15c63804e05b5a94197524023702a259e308 up to, but not including, 3233d8bf7893550045682192cb227af7fa3defeb; e5be15c63804e05b5a94197524023702a259e308 up to, but not including, ec3634ebe23fc3c44ebc67c6d25917300bc68c08; e5be15c63804e05b5a94197524023702a259e308 up to, but not including, 30773ea47d41773f9611ffb4ebc9bda9d19a9e7e; e5be15c63804e05b5a94197524023702a259e308 up to, but not including, 2cf0005d315549b8d2b940ff96a66c2a889aa795; e5be15c63804e05b5a94197524023702a259e308 up to, but not including, 437b5f57732bb4cc32cc9f8895d2010ee9ff521c; e5be15c63804e05b5a94197524023702a259e308 up to, but not including, ded85b0c0edd8f45fec88783d7555a5b982449c1; and 1 more ranges | ec36c134dd020d28e312c2f1766f85525e747aab, 47aa8fcd5e8b5563af4042a00f25ba89bef8f33d, 3233d8bf7893550045682192cb227af7fa3defeb, ec3634ebe23fc3c44ebc67c6d25917300bc68c08, 30773ea47d41773f9611ffb4ebc9bda9d19a9e7e, 2cf0005d315549b8d2b940ff96a66c2a889aa795 |
| Linux | Linux Kernel | before 4.19.306; 4.20 up to, but not including, 5.4.268; 5.5.0 up to, but not including, 5.10.209; 5.11.0 up to, but not including, 5.15.148; 5.16.0 up to, but not including, 6.1.75; 6.2.0 up to, but not including, 6.6.14; 6.7.0 up to, but not including, 6.7.2 | 4.19.306, 5.4.268, 5.10.209, 5.15.148, 6.1.75, 6.6.14 |
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.
Official description
In the Linux kernel, the following vulnerability has been resolved: media: pvrusb2: fix use after free on context disconnection Upon module load, a kthread is created targeting the pvr2_context_thread_func function, which may call pvr2_context_destroy and thus call kfree() on the context object. However, that might happen before the usb hub_event handler is able to notify the driver. This patch adds a sanity check before the invalid read reported by syzbot, within the context disconnection call stack.
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/2cf0005d315549b8d2b940ff96a66c2a889aa795
- git.kernel.org/stable/c/30773ea47d41773f9611ffb4ebc9bda9d19a9e7e
- git.kernel.org/stable/c/3233d8bf7893550045682192cb227af7fa3defeb
- git.kernel.org/stable/c/437b5f57732bb4cc32cc9f8895d2010ee9ff521c
- git.kernel.org/stable/c/47aa8fcd5e8b5563af4042a00f25ba89bef8f33d
- git.kernel.org/stable/c/ded85b0c0edd8f45fec88783d7555a5b982449c1
- git.kernel.org/stable/c/ec3634ebe23fc3c44ebc67c6d25917300bc68c08
- git.kernel.org/stable/c/ec36c134dd020d28e312c2f1766f85525e747aab
Other references
Recent Use After Free vulnerabilities
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