Linux: Use After Free
CVE-2023-53638 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 62312e2f6466b5f0a120542a38b410d88a34ed00, 758c91078165ae641b698750a72eafe7968b3756 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 0.14% 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 62312e2f6466b5f0a120542a38b410d88a34ed00 or 758c91078165ae641b698750a72eafe7968b3756, whichever matches your release line, or a later version.
- Update Linux Kernel to 6.4.12 or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 24d4333233b378114106a1327d3d635a004f4387 up to, but not including, 62312e2f6466b5f0a120542a38b410d88a34ed00; 24d4333233b378114106a1327d3d635a004f4387 up to, but not including, 758c91078165ae641b698750a72eafe7968b3756; 6.4 | 62312e2f6466b5f0a120542a38b410d88a34ed00, 758c91078165ae641b698750a72eafe7968b3756 |
| Linux | Linux Kernel | 6.4 up to, but not including, 6.4.12; 6.5 | 6.4.12 |
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 | 7.0 | High | CNA |
| CVSS 3.1 | 7.8 | High | NVD |
Official description
In the Linux kernel, the following vulnerability has been resolved: octeon_ep: cancel queued works in probe error path If it fails to get the devices's MAC address, octep_probe exits while leaving the delayed work intr_poll_task queued. When the work later runs, it's a use after free. Move the cancelation of intr_poll_task from octep_remove into octep_device_cleanup. This does not change anything in the octep_remove flow, but octep_device_cleanup is called also in the octep_probe error path, where the cancelation is needed. Note that the cancelation of ctrl_mbox_task has to follow intr_poll_task's, because the ctrl_mbox_task may be queued by intr_poll_task.
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
Recent Use After Free vulnerabilities
- 7.8 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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