Linux: Concurrent Execution using Shared Resource with Improper Synchronization
CVE-2026-53361 is a high-severity concurrent execution using shared resource with improper synchronization vulnerability in Linux, with a CVSS 3.1 base score of 7.1 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 20aa894d475bd8086b25c1113ec4ca70f70c7a98, 82c17e13d404f686e164590483fd6c1abaa675d0, 591f1ac217428a6d2b32a8ac14aac0fab44f155a 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 20aa894d475bd8086b25c1113ec4ca70f70c7a98 or 82c17e13d404f686e164590483fd6c1abaa675d0 or 591f1ac217428a6d2b32a8ac14aac0fab44f155a or 0cfa78c050662784fc8e3ab26dbfd1dc632b2082, whichever matches your release line, or a later version.
- Update Linux Kernel to 6.2 or 6.6.144 or 6.12.95 or 6.18.38, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | ceb8bd6c69c1680fd9b45e7f16d7170c9c7513a5 up to, but not including, 20aa894d475bd8086b25c1113ec4ca70f70c7a98; 328840c93bd6a4871dd10908d01b41eab83eb8e2 up to, but not including, 82c17e13d404f686e164590483fd6c1abaa675d0; 8b90a9f819dc2a06baae4ec1a64d875e53b824ec up to, but not including, 591f1ac217428a6d2b32a8ac14aac0fab44f155a; 8b90a9f819dc2a06baae4ec1a64d875e53b824ec up to, but not including, 0cfa78c050662784fc8e3ab26dbfd1dc632b2082; 8b90a9f819dc2a06baae4ec1a64d875e53b824ec up to, but not including, d82ba05263c69fa2437fe93e4e561cc40f4c03af; 6.1.141 up to, but not including, 6.1.183; 6.6.93 up to, but not including, 6.6.144; 6.9 | 20aa894d475bd8086b25c1113ec4ca70f70c7a98, 82c17e13d404f686e164590483fd6c1abaa675d0, 591f1ac217428a6d2b32a8ac14aac0fab44f155a, 0cfa78c050662784fc8e3ab26dbfd1dc632b2082, d82ba05263c69fa2437fe93e4e561cc40f4c03af, 6.1.183 |
| Linux | Linux Kernel | 6.1.141 up to, but not including, 6.2; 6.6.93 up to, but not including, 6.6.144; 6.9 up to, but not including, 6.12.95; 6.13 up to, but not including, 6.18.38; 6.19 up to, but not including, 7.1; 7.1 | 6.2, 6.6.144, 6.12.95, 6.18.38, 7.1 |
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
- NoneNo data is disclosed.
- 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:N/I:H/A:H. Scored by CNA.
Official description
In the Linux kernel, the following vulnerability has been resolved: af_unix: Set gc_in_progress to true in unix_gc(). Igor Ushakov reported that unix_gc() could run with gc_in_progress being false if the work is scheduled while running: Thread 1 Thread 2 Thread 3 -------- -------- -------- unix_schedule_gc() unix_schedule_gc() `- if (!gc_in_progress) `- if (!gc_in_progress) |- gc_in_progress = true | `- queue_work() | unix_gc() <----------------/ | | |- gc_in_progress = true ... `- queue_work() | | `- gc_in_progress = false | | unix_gc() <---------------------------------------------' | ... /* gc_in_progress == false */ | `- gc_in_progress = false unix_peek_fpl() relies on gc_in_progress not to confuse GC by MSG_PEEK. Let's set gc_in_progress to true in unix_gc().
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: partial).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
Other references
Recent Concurrent Execution using Shared Resource with Improper Synchronization vulnerabilities
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- 9.8 Critical severity
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