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High

Double free in Linux kernel USB ULPI ulpi_register_interface() error path

IdentifiersCVE-2026-31759CWE-415· Double Free

CVE-2026-31759 is a Linux kernel memory-management flaw in the USB ULPI subsystem. The bug is in the error path of ulpi_register_interface() when device_register() fails during ULPI device registration. In that failure case, ulpi_register() calls put_device() on ulpi->dev. That in turn invokes the device release callback ulpi_dev_release(), which drops the OF node reference and frees the ulpi structure. The vulnerable error path in ulpi_register_interface() then also calls kfree(ulpi), resulting in a double free of the same object. The upstream fix removes the redundant free and relies on put_device() and ulpi_dev_release() to perform cleanup.

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ANALYST BRIEF

Impact, mitigation & remediation

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Impact

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A successful trigger causes kernel memory corruption due to a double free in kernel space. Depending on allocator state and reachability of the vulnerable path, this can lead to a kernel crash or other undefined behavior, and may create conditions for local privilege escalation or other compromise of kernel integrity. Available scoring context indicates local exploitation with low privileges and no user interaction.

Mitigation

If you can’t patch tonight, do this now.

If immediate patching is not possible, reduce exposure by limiting local untrusted code execution on affected systems, restricting access to kernel-adjacent device-management interfaces, and minimizing use of affected USB/ULPI-related functionality where operationally feasible. Because this is a kernel double-free in an internal error path, no complete mitigation short of installing a fixed kernel is documented in the provided content.

Remediation

Patch, then assume compromise.

Apply a kernel update that includes the upstream fix for CVE-2026-31759. The remediation is to stop freeing ulpi in ulpi_register_interface() after put_device() has already transferred cleanup to ulpi_dev_release(). Vendor advisories indicate fixes have been shipped across multiple SUSE kernel packages, including SLES 12 SP5 LTSS, SLES 15 SP4/SP5/SP6 lines, SLE Micro 5.3/5.4/5.5, and related SAP, HPC, HA, Manager, and openSUSE Leap variants. Reboot after installing the updated kernel.
PUBLIC EXPLOITS

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VALID 0 / 0 TOTALView more in app

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EXPOSURE SURFACE

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VendorProductType
LinuxLinux Kerneloperating_system

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