Linux: Concurrent Execution using Shared Resource with Improper Synchronization
CVE-2024-53186 is a high-severity concurrent execution using shared resource with improper synchronization 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 a96f9eb7add30ba0fafcfe7b7aca090978196800, f20b77f7897e6aab9ce5527e6016ad2be5d70a33, 96261adb998a3b513468b6ce17dbec76be5507d4 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 0.46% 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 a96f9eb7add30ba0fafcfe7b7aca090978196800 or f20b77f7897e6aab9ce5527e6016ad2be5d70a33 or 96261adb998a3b513468b6ce17dbec76be5507d4 or 9a8c5d89d327ff58e9b2517f8a6afb4181d32c6e, whichever matches your release line, or a later version.
- Update Linux Kernel to 6.6.64 or 6.11 or 6.11.11 or 6.12.2, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 18f06bacc197d4ac9b518ad1c69999bc3d83e7aa up to, but not including, a96f9eb7add30ba0fafcfe7b7aca090978196800; e9dac92f4482a382e8c0fe1bc243da5fc3526b0c up to, but not including, f20b77f7897e6aab9ce5527e6016ad2be5d70a33; ee426bfb9d09b29987369b897fe9b6485ac2be27 up to, but not including, 96261adb998a3b513468b6ce17dbec76be5507d4; ee426bfb9d09b29987369b897fe9b6485ac2be27 up to, but not including, 9a8c5d89d327ff58e9b2517f8a6afb4181d32c6e; 9fd3cde4628bcd3549ab95061f2bab74d2ed4f3b; 6.6.55 up to, but not including, 6.6.64; 6.11.3 up to, but not including, 6.11.11; 6.10.14 up to, but not including, 6.11; and 1 more ranges | a96f9eb7add30ba0fafcfe7b7aca090978196800, f20b77f7897e6aab9ce5527e6016ad2be5d70a33, 96261adb998a3b513468b6ce17dbec76be5507d4, 9a8c5d89d327ff58e9b2517f8a6afb4181d32c6e, 6.6.64, 6.11.11 |
| Linux | Linux Kernel | 6.6.55 up to, but not including, 6.6.64; 6.10.14 up to, but not including, 6.11; 6.11.3 up to, but not including, 6.11.11; 6.12 up to, but not including, 6.12.2 | 6.6.64, 6.11, 6.11.11, 6.12.2 |
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 | 9.8 | Critical | CNA |
| CVSS 3.1 | 7.0 | High | NVD |
| CVSS 3.1 | 7.8 | High | CISA (ADP) |
Official description
In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix use-after-free in SMB request handling A race condition exists between SMB request handling in `ksmbd_conn_handler_loop()` and the freeing of `ksmbd_conn` in the workqueue handler `handle_ksmbd_work()`. This leads to a UAF. - KASAN: slab-use-after-free Read in handle_ksmbd_work - KASAN: slab-use-after-free in rtlock_slowlock_locked This race condition arises as follows: - `ksmbd_conn_handler_loop()` waits for `conn->r_count` to reach zero: `wait_event(conn->r_count_q, atomic_read(&conn->r_count) == 0);` - Meanwhile, `handle_ksmbd_work()` decrements `conn->r_count` using `atomic_dec_return(&conn->r_count)`, and if it reaches zero, calls `ksmbd_conn_free()`, which frees `conn`. - However, after `handle_ksmbd_work()` decrements `conn->r_count`, it may still access `conn->r_count_q` in the following line: `waitqueue_active(&conn->r_count_q)` or `wake_up(&conn->r_count_q)` This results in a UAF, as `conn` has already been freed. The discovery of this UAF can be referenced in the following PR for syzkaller's support for SMB requests.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Concurrent Execution using Shared Resource with Improper Synchronization
The product contains a concurrent code sequence that requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence operating concurrently.
How developers prevent this class of flaw
- In languages that support it, use synchronization primitives. Only wrap these around critical code to minimize the impact on performance.
- Use thread-safe capabilities such as the data access abstraction in Spring.
- Minimize the usage of shared resources in order to remove as much complexity as possible from the control flow and to reduce the likelihood of unexpected conditions occurring. Additionally, this will minimize the amount of synchronization necessary and may even help to reduce the likelihood of a denial of service where an attacker may be able to repeatedly trigger a critical section (CWE-400).
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 Concurrent Execution using Shared Resource with Improper Synchronization vulnerabilities
- 7.0 High severity
- 7.0 High severity
- 7.0 High severity
- 7.5 High severity
- 8.1 High severity
- 7.8 High severity
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