CVE-2023-52597: In the Linux kernel, the following vulnerability has been resolved: KVM: s390: fix setting of fpc register kvm_arch_vcpu_ioctl_set

In the Linux kernel, the following vulnerability has been resolved: KVM: s390: fix setting of fpc register kvm_arch_vcpu_ioctl_set_fpu() allows to set the flo

In the Linux kernel, the following vulnerability has been resolved: KVM: s390: fix setting of fpc register kvm_arch_vcpu_ioctl_set_fpu() allows to set the floating point control (fpc) register of a guest cpu. The new value is tested for validity by temporarily loading it into the fpc register. This may lead to corruption of the fpc register of the host process: if an interrupt happens while the value is temporarily loaded into the fpc register, and within interrupt context floating point or vector registers are used, the current fp/vx registers are saved with save_fpu_regs() assuming they belong to user space and will be loaded into fp/vx registers when returning to user space. test_fp_ctl() restores the original user space / host process fpc register value, however it will be discarded, when returning to user space. In result the host process will incorrectly continue to run with the value that was supposed to be used for a guest cpu. Fix this by simply removing the test. There is another test right before the SIE context is entered which will handles invalid values. This results in a change of behaviour: invalid values will now be accepted instead of that the ioctl fails w

Description from the National Vulnerability Database, published by 416baaa9-dc9f-4396-8d5f-8c081fb06d67

What it means for a small business

Linux is on the computers, phones or browsers your team uses every day. Turn on automatic updates and restart: most of these fixes only take effect after a restart.

How likely is an attack? The Exploit Prediction Scoring System, run by FIRST (the global association of security response teams), puts the odds of this one being exploited in the next 30 days at 0.23%, higher than 14% of CVEs. That’s low, but low isn’t zero, and the odds jump the day someone publishes an exploit. Scored October 29, 2026, updated daily.

Check your own setup

Website check: reads what your site runs from the outside (WordPress version, plugins it can see, old server software) and matches it against this database.
Server check: what your web server says about itself, and whether that version has known flaws.

Sources

Part of the Huttenlocher Technologies vulnerability database, refreshed twice a day from CISA and the NVD. The title, category and plain-language guidance are ours; check the linked record before acting on a detail. This is general guidance, not a review of your systems.

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