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CVE-2026-64213 Linux CVE debrief

A concurrency issue in the Linux kernel's hwmon lm90 driver can cause an interrupt storm when an alert interrupt occurs concurrently with a sysfs write operation. This issue arises because lm90_alert() executes in the smbus alert context and calls lm90_update_confreg() to disable the hardware alert line without acquiring hwmon_lock. Concurrently, sysfs write operations hold hwmon_lock, temporarily modify data->config, and then restore it. If an alert interrupt occurs concurrently with a sysfs write, the sysfs path overwrites the alert handler's modifications to data->config and the hardware register, unintentionally re-enabling the hardware alert line while the alarm is still active. This can lead to system instability and potential security risks if not addressed. Linux system administrators and users, especially those with systems using the lm90 driver, should be aware of this issue and apply the necessary patches to prevent potential interrupt storms and system instability. The official patches should be applied to update the lm90 driver and ensure proper locking to prevent interrupt storms.

Vendor
Linux
Product
Unknown
CVSS
MEDIUM 5.5
CISA KEV
Not listed in stored evidence
Original CVE published
2026-07-24
Original CVE updated
2026-08-11
Advisory published
2026-07-24
Advisory updated
2026-08-11

Who should care

Linux system administrators and users, especially those with systems using the lm90 driver, should be aware of this issue and apply the necessary patches to prevent potential interrupt storms and system instability.

Technical summary

The Linux kernel's hwmon lm90 driver has a concurrency issue. lm90_alert() executes in the smbus alert context and calls lm90_update_confreg() to disable the hardware alert line without acquiring hwmon_lock. Concurrent sysfs write operations hold hwmon_lock, modify data->config, and then restore it. If an alert interrupt occurs concurrently with a sysfs write, the sysfs path overwrites the alert handler's modifications to data->config and the hardware register, causing an interrupt storm.

Defensive priority

Apply the official patches to update the lm90 driver and ensure proper locking to prevent interrupt storms.

Recommended defensive actions

  • Apply patches from https://git.kernel.org/stable/c/873e919e3101063a7a75989510ccfc125a4391cf
  • Apply patches from https://git.kernel.org/stable/c/b0b66aae8a94c3663d47e4000b0e81b89ce32186
  • Apply patches from https://git.kernel.org/stable/c/bed1fc32e0eb653806fa98afcf55f9a311fc4ce2
  • Inventory Linux systems for lm90 driver usage and ensure patch deployment
  • Monitor for unusual interrupt activity on systems with lm90 driver

Evidence notes

The issue arises from lm90_alert() executing in the smbus alert context and calling lm90_update_confreg() to disable the hardware alert line without acquiring hwmon_lock. Concurrent sysfs write operations hold hwmon_lock, modify data->config, and then restore it. If an alert interrupt occurs concurrently with a sysfs write, the sysfs path overwrites the alert handler's modifications to data->config and the hardware register, unintentionally re-enabling the hardware alert line while the alarm is still active.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-64213 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-64213

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-64213 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-64213

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

  • Mitigation or vendor reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/873e919e3101063a7a75989510ccfc125a4391cf

    416baaa9-dc9f-4396-8d5f-8c081fb06d67 - Patch

  • Mitigation or vendor reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/b0b66aae8a94c3663d47e4000b0e81b89ce32186

    416baaa9-dc9f-4396-8d5f-8c081fb06d67 - Patch

  • Mitigation or vendor reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/bed1fc32e0eb653806fa98afcf55f9a311fc4ce2

    416baaa9-dc9f-4396-8d5f-8c081fb06d67 - Patch

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.