PatchSiren

PatchSiren cyber security CVE debrief

CVE-2026-23443 Linux CVE debrief

A use-after-free vulnerability was found in the Linux kernel. After a previous fix for acpi_processor_errata_piix4(), device pointers may be dereferenced after dropping references to the device objects pointed to by them, which may cause a use-after-free to occur. Moreover, debug messages about enabling the errata may be printed if the errata flags corresponding to them are unset. Address all of these issues by moving message printing to the points in the code where the errata flags are set. This vulnerability affects Linux kernel versions 6.1.165 to 6.1.167, 6.6.128 to 6.6.130, 6.12.75 to 6.12.78, 6.18.16 to 6.18.20, and 6.19.6 to 6.19.10, and 5.15.202.

Vendor
Linux
Product
Unknown
CVSS
MEDIUM 5.5
CISA KEV
Not listed in stored evidence
Original CVE published
2026-04-03
Original CVE updated
2026-07-24
Advisory published
2026-04-03
Advisory updated
2026-07-24

Who should care

Users of Linux kernel versions 6.1.165 to 6.1.167, 6.6.128 to 6.6.130, 6.12.75 to 6.12.78, 6.18.16 to 6.18.20, and 6.19.6 to 6.19.10, and 5.15.202 should be aware of this vulnerability. System administrators and security teams responsible for Linux kernel-based systems should assess their configurations and apply necessary patches or mitigations.

Technical summary

The vulnerability is caused by a use-after-free error in the acpi_processor_errata_piix4() function. This function is part of the ACPI processor driver in the Linux kernel. The issue arises when device pointers are dereferenced after the references to the device objects they point to have been dropped. This can lead to unexpected behavior or crashes. Additionally, there is an issue with debug messages being printed even when the corresponding errata flags are not set. The fix involves moving the printing of messages to where the errata flags are set, ensuring that messages are only printed when the flags are actually set.

Defensive priority

Medium

Recommended defensive actions

  • Inventory and assess Linux kernel versions in use
  • Apply patches from kernel.org
  • Monitor system logs for unusual activity
  • Consider compensating controls such as SELinux or AppArmor
  • Review system configurations for potential exposure
  • Track exceptions and retest remediated assets
  • Confirm whether affected product deployments exist in managed environments

Evidence notes

The CVE record was published on 2026-04-03T16:16:28.573Z and was last modified on 2026-07-24T21:10:00.143Z. The NVD entry is currently Analyzed. This vulnerability affects Linux kernel versions 6.1.165 to 6.1.167, 6.6.128 to 6.6.130, 6.12.75 to 6.12.78, 6.18.16 to 6.18.20, and 6.19.6 to 6.19.10, and 5.15.202. Users should verify their system configurations and apply patches or mitigations as recommended by the Linux kernel community.

Official resources

AI-assisted PatchSiren debrief based on the supplied source corpus. The CVE record was published on 2026-04-03T16:16:28.573Z and has not been modified since then. The NVD entry is currently Analyzed.