CVE-2024-55881: In the Linux kernel, the following vulnerability has been resolved: KVM: x86: Play nice with protected guests in complete_hypercall_exit() Use is_64...

Description

In the Linux kernel, the following vulnerability has been resolved: KVM: x86: Play nice with protected guests in complete_hypercall_exit() Use is_64_bit_hypercall() instead of is_64_bit_mode() to detect a 64-bit hypercall when completing said hypercall. For guests with protected state, e.g. SEV-ES and SEV-SNP, KVM must assume the hypercall was made in 64-bit mode as the vCPU state needed to detect 64-bit mode is unavailable. Hacking the sev_smoke_test selftest to generate a KVM_HC_MAP_GPA_RANGE hypercall via VMGEXIT trips the WARN: ------------[ cut here ]------------ WARNING: CPU: 273 PID: 326626 at arch/x86/kvm/x86.h:180 complete_hypercall_exit+0x44/0xe0 [kvm] Modules linked in: kvm_amd kvm ... [last unloaded: kvm] CPU: 273 UID: 0 PID: 326626 Comm: sev_smoke_test Not tainted 6.12.0-smp--392e932fa0f3-feat #470 Hardware name: Google Astoria/astoria, BIOS 0.20240617.0-0 06/17/2024 RIP: 0010:complete_hypercall_exit+0x44/0xe0 [kvm] Call Trace: <TASK> kvm_arch_vcpu_ioctl_run+0x2400/0x2720 [kvm] kvm_vcpu_ioctl+0x54f/0x630 [kvm] __se_sys_ioctl+0x6b/0xc0 do_syscall_64+0x83/0x160 entry_SYSCALL_64_after_hwframe+0x76/0x7e </TASK> ---[ end trace 0000000000000000 ]---

Metrics

CVSS 3.1

5.5/10

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

EPSS Probability

0.20%

10.3th percentile

Probability of exploitation in the next 30 days. Learn more

Affected Software

Vendor	Product	Versions	Update
Linux	Linux Kernel	>= 5.15.5, < 5.15.176	—
Linux	Linux Kernel	>= 5.16.1, < 6.1.122	—
Linux	Linux Kernel	>= 6.2, < 6.6.68	—
Linux	Linux Kernel	>= 6.7, < 6.12.7	—
Linux	Linux Kernel	5.16	—
Linux	Linux Kernel	6.13	Rc1

References

Timeline

Published: Jan 11, 2025
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2024-55881?

In the Linux kernel, the following vulnerability has been resolved: KVM: x86: Play nice with protected guests in complete_hypercall_exit() Use is_64_bit_hypercall() instead of is_64_bit_mode() to detect a 64-bit hypercall when completing said hypercall. For guests with protected state, e.g. SEV-ES and SEV-SNP, KVM must assume the hypercall was made in 64-bit mode as the vCPU state needed to detect 64-bit mode is unavailable. Hacking the sev_smoke_test selftest to generate a KVM_HC_MAP_GPA_RANGE hypercall via VMGEXIT trips the WARN: ------------[ cut here ]------------ WARNING: CPU: 273 PID: 326626 at arch/x86/kvm/x86.h:180 complete_hypercall_exit+0x44/0xe0 [kvm] Modules linked in: kvm_amd kvm ... [last unloaded: kvm] CPU: 273 UID: 0 PID: 326626 Comm: sev_smoke_test Not tainted 6.12.0-smp--392e932fa0f3-feat #470 Hardware name: Google Astoria/astoria, BIOS 0.20240617.0-0 06/17/2024 RIP: 0010:complete_hypercall_exit+0x44/0xe0 [kvm] Call Trace: <TASK> kvm_arch_vcpu_ioctl_run+0x2400/0x2720 [kvm] kvm_vcpu_ioctl+0x54f/0x630 [kvm] __se_sys_ioctl+0x6b/0xc0 do_syscall_64+0x83/0x160 entry_SYSCALL_64_after_hwframe+0x76/0x7e </TASK> ---[ end trace 0000000000000000 ]---

How severe is CVE-2024-55881?

CVE-2024-55881 has a CVSS score of 5.5/10 (MEDIUM severity). The EPSS model estimates a 0.20% probability of exploitation in the next 30 days.

How do I fix CVE-2024-55881?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.