Linux: Use After Free
CVE-2023-53494 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 92a07ba4f0af2cccdc2aa5ee32679c9c9714db90, 912eb10b65646ffd222256c78a1c566a3dac177d, 57c3e1d63b63dc0841d41df729297cd7c1c35808 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 0.16% 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 92a07ba4f0af2cccdc2aa5ee32679c9c9714db90 or 912eb10b65646ffd222256c78a1c566a3dac177d or 57c3e1d63b63dc0841d41df729297cd7c1c35808 or d5870848879291700fe6c5257dcb48aadd10425c, whichever matches your release line, or a later version.
- Update Linux Kernel to 5.10.173 or 5.15.99 or 6.1.16 or 6.2.3, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 8083b1bf8163e7ae7d8c90f221106d96450b8aa8 up to, but not including, 92a07ba4f0af2cccdc2aa5ee32679c9c9714db90; 8083b1bf8163e7ae7d8c90f221106d96450b8aa8 up to, but not including, 912eb10b65646ffd222256c78a1c566a3dac177d; 8083b1bf8163e7ae7d8c90f221106d96450b8aa8 up to, but not including, 57c3e1d63b63dc0841d41df729297cd7c1c35808; 8083b1bf8163e7ae7d8c90f221106d96450b8aa8 up to, but not including, d5870848879291700fe6c5257dcb48aadd10425c; 8083b1bf8163e7ae7d8c90f221106d96450b8aa8 up to, but not including, 51c082514c2dedf2711c99d93c196cc4eedceb40; 5.4 | 92a07ba4f0af2cccdc2aa5ee32679c9c9714db90, 912eb10b65646ffd222256c78a1c566a3dac177d, 57c3e1d63b63dc0841d41df729297cd7c1c35808, d5870848879291700fe6c5257dcb48aadd10425c, 51c082514c2dedf2711c99d93c196cc4eedceb40 |
| Linux | Linux Kernel | 5.4 up to, but not including, 5.10.173; 5.11 up to, but not including, 5.15.99; 5.16 up to, but not including, 6.1.16; 6.2 up to, but not including, 6.2.3 | 5.10.173, 5.15.99, 6.1.16, 6.2.3 |
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: crypto: xts - Handle EBUSY correctly As it is xts only handles the special return value of EINPROGRESS, which means that in all other cases it will free data related to the request. However, as the caller of xts may specify MAY_BACKLOG, we also need to expect EBUSY and treat it in the same way. Otherwise backlogged requests will trigger a use-after-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.
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
- git.kernel.org/stable/c/51c082514c2dedf2711c99d93c196cc4eedceb40
- git.kernel.org/stable/c/57c3e1d63b63dc0841d41df729297cd7c1c35808
- git.kernel.org/stable/c/912eb10b65646ffd222256c78a1c566a3dac177d
- git.kernel.org/stable/c/92a07ba4f0af2cccdc2aa5ee32679c9c9714db90
- git.kernel.org/stable/c/d5870848879291700fe6c5257dcb48aadd10425c
Recent Use After Free vulnerabilities
- 8.1 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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