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Linux KernelOperating system · Linux

CVE-2026-64205

MEDIUM · 5.5 CVSS v3.1 Published 2026-07-20
Fix available
A fix is available. Upgrade to 6.6.148 / 6.12.101 or later.
See remediation →
57/100
Remediation priority · Elevated
Zero-click 4 weeks old

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
In the Linux kernel, the following vulnerability has been resolved: i2c: i801: fix hardware state machine corruption in error path A severe livelock and subsequent Hung Task panic were observed in the i2c-i801 driver during concurrent Fuzzing. The crash is caused by an unconditional hardware register cleanup in the error handling path of i801_access(). When i801_check_pre() fails (e.g., returning -EBUSY because the SMBus controller is actively used by BIOS/ACPI), the kernel does not actually acquire the hardware ownership. However, the code jumps to the 'out' label and executes: iowrite8(SMBHSTSTS_INUSE_STS | STATUS_FLAGS, SMBHSTSTS(priv)); This forcefully clears the INUSE_STS lock and resets the hardware status flags without owning the controller. Doing so interrupts ongoing BIOS/ACPI transactions and totally corrupts the SMBus hardware state machine. Consequently, all subsequent i801_access() calls fail at the pre-check stage, triggering an endless stream of "SMBus is busy, can't use it!" error logs. Over a slow serial console, this printk flood monopolizes the CPU (Console Livelock), starving other processes trying to acquire the mmap_lock down_read semaphore, ultimately triggering the hung task watchdog. Fix this by moving the 'out' label below the hardware register cleanup. If i801_check_pre() fails, we safely bypass the iowrite8() and only release the software locks (pm_runtime and mutex), strictly adhering to the rule of not releasing resources that were never acquired.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis

A detailed technical summary for this CVE is being prepared.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Linux KernelOperating system
Affected:>= 6.3, < 6.6.148>= 6.7, < 6.12.101>= 6.13, < 6.18.39>= 6.19, < 7.1.4

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Local
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 6.6.148 / 6.12.101 / 6.18.39 or later
Fixed in 6.6.1486.12.1016.18.39
Recommended fix High confidence

Upgrade to kernel version 6.6.148, 6.12.101, 6.18.39, or 7.1.4 or later (whichever is the next stable release for your base branch)

  1. Obtain the kernel source code for your currently running kernel version from the affected range (>= 6.3, < 6.6.148; >= 6.7, < 6.12.101; >= 6.13, < 6.18.39; >= 6.19, < 7.1.4)
  2. Locate the i2c-i801 driver source file (typically drivers/i2c/busses/i2c-i801.c)
  3. Find the i801_access() function and identify the error handling path that unconditionally executes iowrite8(SMBHSTSTS_INUSE_STS | STATUS_FLAGS, SMBHSTSTS(priv)) at the 'out' label
  4. Apply the fix: move the iowrite8() hardware register cleanup code from the 'out' label to after the successful hardware acquisition path, and create a new 'out_unlock' label that only releases software locks (pm_runtime_put() and mutex) for the i801_check_pre() failure case
  5. Recompile the kernel with the patched i2c-i801 driver
  6. Reboot the system with the patched kernel
Caveat This is a bugfix with minimal risk; only affects error path behavior in the i801 i2c driver

Generated from the published advisory — verify against the referenced sources before acting.

We can perform the upgrade in your staging environment and verify nothing breaks — typical engagement from $1,600. Get the upgrade done

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

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