Linux: Concurrent Execution using Shared Resource with Improper Synchronization
CVE-2026-23239 is a high-severity concurrent execution using shared resource with improper synchronization 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 f7ad8b1d0e421c524604d5076b73232093490d5c, 664e9df53226b4505a0894817ecad2c610ab11d8, 022ff7f347588de6e17879a1da6019647b21321b 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 0.13% 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 f7ad8b1d0e421c524604d5076b73232093490d5c or 664e9df53226b4505a0894817ecad2c610ab11d8 or 022ff7f347588de6e17879a1da6019647b21321b or e1512c1db9e8794d8d130addd2615ec27231d994, whichever matches your release line, or a later version.
- Update Linux Kernel to 6.12.75 or 6.18.16 or 6.19.6, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | e27cca96cd68fa2c6814c90f9a1cfd36bb68c593 up to, but not including, f7ad8b1d0e421c524604d5076b73232093490d5c; e27cca96cd68fa2c6814c90f9a1cfd36bb68c593 up to, but not including, 664e9df53226b4505a0894817ecad2c610ab11d8; e27cca96cd68fa2c6814c90f9a1cfd36bb68c593 up to, but not including, 022ff7f347588de6e17879a1da6019647b21321b; e27cca96cd68fa2c6814c90f9a1cfd36bb68c593 up to, but not including, e1512c1db9e8794d8d130addd2615ec27231d994; 5.6 | f7ad8b1d0e421c524604d5076b73232093490d5c, 664e9df53226b4505a0894817ecad2c610ab11d8, 022ff7f347588de6e17879a1da6019647b21321b, e1512c1db9e8794d8d130addd2615ec27231d994 |
| Linux | Linux Kernel | 5.6 up to, but not including, 6.12.75; 6.13 up to, but not including, 6.18.16; 6.19 up to, but not including, 6.19.6; 7.0 | 6.12.75, 6.18.16, 6.19.6 |
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 CNA.
Official description
In the Linux kernel, the following vulnerability has been resolved: espintcp: Fix race condition in espintcp_close() This issue was discovered during a code audit. After cancel_work_sync() is called from espintcp_close(), espintcp_tx_work() can still be scheduled from paths such as the Delayed ACK handler or ksoftirqd. As a result, the espintcp_tx_work() worker may dereference a freed espintcp ctx or sk. The following is a simple race scenario: cpu0 cpu1 espintcp_close() cancel_work_sync(&ctx->work); espintcp_write_space() schedule_work(&ctx->work); To prevent this race condition, cancel_work_sync() is replaced with disable_work_sync().
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
- 7.1 High severity
- 7.4 High severity
- 7.0 High severity
- 7.0 High severity
- 7.0 High severity
- 7.0 High severity
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