Linux: Concurrent Execution using Shared Resource with Improper Synchronization
CVE-2026-23275 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 7cc4530b3e952d4a5947e1e55d06620d8845d4f5, 46dc07d5f31411cc023f3bf1f4a23a07bf6e0ed1, 96189080265e6bb5dde3a4afbaf947af493e3f82 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 0.1% 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 7cc4530b3e952d4a5947e1e55d06620d8845d4f5 or 46dc07d5f31411cc023f3bf1f4a23a07bf6e0ed1 or 96189080265e6bb5dde3a4afbaf947af493e3f82, whichever matches your release line, or a later version.
- Update Linux Kernel to 6.18.19 or 6.19.9, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 79cfe9e59c2a12c3b3faeeefe38d23f3d8030972 up to, but not including, 7cc4530b3e952d4a5947e1e55d06620d8845d4f5; 79cfe9e59c2a12c3b3faeeefe38d23f3d8030972 up to, but not including, 46dc07d5f31411cc023f3bf1f4a23a07bf6e0ed1; 79cfe9e59c2a12c3b3faeeefe38d23f3d8030972 up to, but not including, 96189080265e6bb5dde3a4afbaf947af493e3f82; 6.13 | 7cc4530b3e952d4a5947e1e55d06620d8845d4f5, 46dc07d5f31411cc023f3bf1f4a23a07bf6e0ed1, 96189080265e6bb5dde3a4afbaf947af493e3f82 |
| Linux | Linux Kernel | 6.13 up to, but not including, 6.18.19; 6.19 up to, but not including, 6.19.9; 7.0 | 6.18.19, 6.19.9 |
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: io_uring: ensure ctx->rings is stable for task work flags manipulation If DEFER_TASKRUN | SETUP_TASKRUN is used and task work is added while the ring is being resized, it's possible for the OR'ing of IORING_SQ_TASKRUN to happen in the small window of swapping into the new rings and the old rings being freed. Prevent this by adding a 2nd ->rings pointer, ->rings_rcu, which is protected by RCU. The task work flags manipulation is inside RCU already, and if the resize ring freeing is done post an RCU synchronize, then there's no need to add locking to the fast path of task work additions. Note: this is only done for DEFER_TASKRUN, as that's the only setup mode that supports ring resizing. If this ever changes, then they too need to use the io_ctx_mark_taskrun() helper.
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
- 7.4 High severity
- 7.8 High severity
- 7.4 High severity
- 7.1 High severity
- 7.4 High severity
- 7.0 High severity
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