https://vulnerability.circl.lu Contains only the most 10 recent entries. http://www.rssboard.org/rss-specification python-feedgen en Tue, 06 Oct 2026 02:17:16 +0000 https://vulnerability.circl.lu/vuln/cve-2025-40300 <p><strong>Affected:</strong> Linux, Siemens SIMATIC CN 4100, Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP, Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP, Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP</p> <p>In the Linux kernel, the following vulnerability has been resolved:</p> <p>x86/vmscape: Add conditional IBPB mitigation</p> <p>VMSCAPE is a vulnerability that exploits insufficient branch predictor isolation between a guest and a userspace hypervisor (like QEMU). Existing mitigations already protect kernel/KVM from a malicious guest. Userspace can additionally be protected by flushing the branch predictors after a VMexit.</p> <p>Since it is the userspace that consumes the poisoned branch predictors, conditionally issue an IBPB after a VMexit and before returning to userspace. Workloads that frequently switch between hypervisor and userspace will incur the most overhead from the new IBPB.</p> <p>This new IBPB is not integrated with the existing IBPB sites. For instance, a task can use the existing speculation control prctl() to get an IBPB at context switch time. With this implementation, the IBPB is doubled up: one at context switch and another before running userspace.</p> <p>The intent is to integrate and optimize these cases post-embargo.</p> <p>[ dhansen: elaborate on suboptimal IBPB solution ]</p> <p><strong>Affected:</strong> Linux, Siemens SIMATIC CN 4100, Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP, Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP, Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP</p> <p>In the Linux kernel, the following vulnerability has been resolved:</p> <p>x86/vmscape: Add conditional IBPB mitigation</p> <p>VMSCAPE is a vulnerability that exploits insufficient branch predictor isolation between a guest and a userspace hypervisor (like QEMU). Existing mitigations already protect kernel/KVM from a malicious guest. Userspace can additionally be protected by flushing the branch predictors after a VMexit.</p> <p>Since it is the userspace that consumes the poisoned branch predictors, conditionally issue an IBPB after a VMexit and before returning to userspace. Workloads that frequently switch between hypervisor and userspace will incur the most overhead from the new IBPB.</p> <p>This new IBPB is not integrated with the existing IBPB sites. For instance, a task can use the existing speculation control prctl() to get an IBPB at context switch time. With this implementation, the IBPB is doubled up: one at context switch and another before running userspace.</p> <p>The intent is to integrate and optimize these cases post-embargo.</p> <p>[ dhansen: elaborate on suboptimal IBPB solution ]</p> https://vulnerability.circl.lu/vuln/cve-2025-40300