Linux: Use After Free
CVE-2023-52503 is a high-severity use after free vulnerability in Linux, with a CVSS 3.1 base score of 7.0 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 da7ce52a2f6c468946195b116615297d3d113a27, 1680c82929bc14d706065f123dab77f2f1293116, 60c3e7a00db954947c265b55099c21b216f2a05c 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 0.26% 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 da7ce52a2f6c468946195b116615297d3d113a27 or 1680c82929bc14d706065f123dab77f2f1293116 or 60c3e7a00db954947c265b55099c21b216f2a05c or 1c95574350cd63bc3c5c2fa06658010768f2a0ce, whichever matches your release line, or a later version.
- Update Linux Kernel to 5.10.199 or 5.15.136 or 6.1.59 or 6.5.8, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 757cc3e9ff1d72d014096399d6e2bf03974d9da1 up to, but not including, da7ce52a2f6c468946195b116615297d3d113a27; 757cc3e9ff1d72d014096399d6e2bf03974d9da1 up to, but not including, 1680c82929bc14d706065f123dab77f2f1293116; 757cc3e9ff1d72d014096399d6e2bf03974d9da1 up to, but not including, 60c3e7a00db954947c265b55099c21b216f2a05c; 757cc3e9ff1d72d014096399d6e2bf03974d9da1 up to, but not including, 1c95574350cd63bc3c5c2fa06658010768f2a0ce; 757cc3e9ff1d72d014096399d6e2bf03974d9da1 up to, but not including, f4384b3e54ea813868bb81a861bf5b2406e15d8f; 5.6 | da7ce52a2f6c468946195b116615297d3d113a27, 1680c82929bc14d706065f123dab77f2f1293116, 60c3e7a00db954947c265b55099c21b216f2a05c, 1c95574350cd63bc3c5c2fa06658010768f2a0ce, f4384b3e54ea813868bb81a861bf5b2406e15d8f |
| Linux | Linux Kernel | 5.6 up to, but not including, 5.10.199; 5.11 up to, but not including, 5.15.136; 5.16 up to, but not including, 6.1.59; 6.2 up to, but not including, 6.5.8; 6.6 | 5.10.199, 5.15.136, 6.1.59, 6.5.8 |
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
- HighSuccess depends on conditions outside the attacker's control.
- 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:H/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 | 7.0 | High | NVD |
Official description
In the Linux kernel, the following vulnerability has been resolved: tee: amdtee: fix use-after-free vulnerability in amdtee_close_session There is a potential race condition in amdtee_close_session that may cause use-after-free in amdtee_open_session. For instance, if a session has refcount == 1, and one thread tries to free this session via: kref_put(&sess->refcount, destroy_session); the reference count will get decremented, and the next step would be to call destroy_session(). However, if in another thread, amdtee_open_session() is called before destroy_session() has completed execution, alloc_session() may return 'sess' that will be freed up later in destroy_session() leading to use-after-free in amdtee_open_session. To fix this issue, treat decrement of sess->refcount and removal of 'sess' from session list in destroy_session() as a critical section, so that it is executed atomically.
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/1680c82929bc14d706065f123dab77f2f1293116
- git.kernel.org/stable/c/1c95574350cd63bc3c5c2fa06658010768f2a0ce
- git.kernel.org/stable/c/60c3e7a00db954947c265b55099c21b216f2a05c
- git.kernel.org/stable/c/da7ce52a2f6c468946195b116615297d3d113a27
- git.kernel.org/stable/c/f4384b3e54ea813868bb81a861bf5b2406e15d8f
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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