Linux: Improper Locking
CVE-2026-43253 is a high-severity improper locking vulnerability in Linux, with a CVSS 3.1 base score of 7.5 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists versions 69d9339c02eddfc2a345be7220651068a3684383, f2f65b28d802a667119147444ec2ae33eebf9a58, 715c263119fd1b918a9fcbd8a36ea5b604a46324 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 0.37% 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 69d9339c02eddfc2a345be7220651068a3684383 or f2f65b28d802a667119147444ec2ae33eebf9a58 or 715c263119fd1b918a9fcbd8a36ea5b604a46324 or e15768e68820142077bbca402d8e902f64ade1b0, whichever matches your release line, or a later version.
- Update Linux Kernel to 6.6.128 or 6.12.75 or 6.18.16 or 6.19.6, whichever matches your release line, or a later version.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 4bf5beef578e46393f11eb69dda7d17a065e05ff up to, but not including, 69d9339c02eddfc2a345be7220651068a3684383; 4bf5beef578e46393f11eb69dda7d17a065e05ff up to, but not including, f2f65b28d802a667119147444ec2ae33eebf9a58; 4bf5beef578e46393f11eb69dda7d17a065e05ff up to, but not including, 715c263119fd1b918a9fcbd8a36ea5b604a46324; 4bf5beef578e46393f11eb69dda7d17a065e05ff up to, but not including, e15768e68820142077bbca402d8e902f64ade1b0; 4bf5beef578e46393f11eb69dda7d17a065e05ff up to, but not including, 496269d12072ecb219826485bdbec70c92a8eef5; 4bf5beef578e46393f11eb69dda7d17a065e05ff up to, but not including, d2a0cac10597068567d336e85fa3cbdbe8ca62bf; 4.9 | 69d9339c02eddfc2a345be7220651068a3684383, f2f65b28d802a667119147444ec2ae33eebf9a58, 715c263119fd1b918a9fcbd8a36ea5b604a46324, e15768e68820142077bbca402d8e902f64ade1b0, 496269d12072ecb219826485bdbec70c92a8eef5, d2a0cac10597068567d336e85fa3cbdbe8ca62bf |
| Linux | Linux Kernel | 4.9 up to, but not including, 6.6.128; 6.7 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 | 6.6.128, 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
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- NoneNo data is disclosed.
- Integrity
- NoneNothing can be modified.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H. Scored by CNA.
Official description
In the Linux kernel, the following vulnerability has been resolved: iommu/amd: move wait_on_sem() out of spinlock With iommu.strict=1, the existing completion wait path can cause soft lockups under stressed environment, as wait_on_sem() busy-waits under the spinlock with interrupts disabled. Move the completion wait in iommu_completion_wait() out of the spinlock. wait_on_sem() only polls the hardware-updated cmd_sem and does not require iommu->lock, so holding the lock during the busy wait unnecessarily increases contention and extends the time with interrupts disabled.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Improper Locking
The product does not properly acquire or release a lock on a resource, leading to unexpected resource state changes and behaviors.
How developers prevent this class of flaw
- Use industry standard APIs to implement locking mechanism.
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
- git.kernel.org/stable/c/496269d12072ecb219826485bdbec70c92a8eef5
- git.kernel.org/stable/c/715c263119fd1b918a9fcbd8a36ea5b604a46324
- git.kernel.org/stable/c/d2a0cac10597068567d336e85fa3cbdbe8ca62bf
- git.kernel.org/stable/c/e15768e68820142077bbca402d8e902f64ade1b0
- git.kernel.org/stable/c/f2f65b28d802a667119147444ec2ae33eebf9a58
Other references
Recent Improper Locking vulnerabilities
- 8.8 High severity
- 7.8 High severity
- 7.5 High severity
- 7.8 High severity
- 8.8 High severity
- 7.5 High severity
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