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CVE-2023-52597 is a low-severity flaw in the Linux kernel's KVM implementation for IBM s390 systems. When KVM uses an ioctl to set a guest vCPU floating-point-unit state, it temporarily loads a floating-point control (FPC) value while validating it; an interrupt that uses floating-point or vector registers during that window can corrupt the host process's FPC register. Red Hat rates the issue CVSS 4.0 (AV:L/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:L) and classifies it as improper input validation (CWE-20).
Red Hat issued fixes for RHEL 8 kernel and kernel-rt packages and RHEL 9 kernel packages. RHEL 9 kernel-rt remained affected at the time of the advisory, while RHEL 6 and RHEL 7 kernel variants were outside support scope. Organizations operating KVM workloads on IBM s390 should identify affected kernel packages and apply the available updates, prioritizing systems where untrusted or highly privileged guest-management operations are permitted.
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Red Hat released RHSA-2024:2950 for the RHEL 8 kernel-rt and RHSA-2024:3138 for the RHEL 8 kernel, fixing CVE-2023-52597. The issue affects KVM virtualization support on IBM s390 systems.
Red Hat released RHSA-2024:2394 to address CVE-2023-52597 in the Red Hat Enterprise Linux 9 kernel. The KVM s390 flaw could corrupt a host process's floating-point control register during guest vCPU FPU-state handling.
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**CVE-2022-39189** affects the Linux kernel’s x86 KVM subsystem, where instruction emulation can leave the `KVM_VCPU_PREEMPTED` flag set and mishandle paravirtualized TLB flushes. Other guest vCPUs may then skip required TLB-flush IPIs while emulation accesses memory using stale guest-virtual translations, enabling an unprivileged user inside a VM to compromise the guest kernel or cause guest malfunction. The issue affects the `KVM_FEATURE_PV_TLB_FLUSH` functionality introduced in Linux 4.16 and was demonstrated through emulated VMMCALL and port-I/O operations. The upstream correction, commit `6cd88243c7e03845a450795e134b488fc2afb736`, was merged for Linux 5.19 and backported to the stable 5.15 and 5.18 kernel trees; affected kernels are generally versions before 5.18.17. Red Hat rated the vulnerability Moderate with CVSS 7.0 and issued fixes for affected RHEL 8, RHEL 8 kernel-rt, RHEL 8.6 EUS, RHEL 9, RHEL 9 kernel-rt, and Red Hat Virtualization 4 on RHEL 8 packages; Red Hat reported no qualifying mitigation, making deployment of the relevant kernel updates the required remediation.
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A vulnerability tracked as **CVE-2023-46813** affects the Linux kernel's handling of AMD Secure Encrypted Virtualization (SEV) guests. A low-privileged local user in an SEV virtual machine can use MMIO/string I/O exception-emulation paths to trigger a buffer overflow or null-pointer dereference, potentially causing a denial of service or escalating privileges. Red Hat rates the issue **CVSS 7.0** and categorizes it as improper privilege management (`CWE-269`). Linux fixed the flaw by adding validation in the x86 SEV exception-emulation code before string I/O reads and writes. The new `vc_insn_string_check()` rejects user-space I/O operations whose addresses point into kernel space and raises a user page fault instead. Red Hat issued fixes for affected RHEL 8 and RHEL 9 kernel variants and Red Hat Virtualization 4 on RHEL 8; it reported no generally suitable mitigation beyond applying the relevant updates.
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