x86/hyperv: Disable IBT when hypercall page lacks ENDBR instruction
In the Linux kernel, the following vulnerability has been resolved:
x86/hyperv: Disable IBT when hypercall page lacks ENDBR instruction
On hardware that supports Indirect Branch Tracking (IBT), Hyper-V VMs
with ConfigVersion 9.3 or later support IBT in the guest. However,
current versions of Hyper-V have a bug in that there's not an ENDBR64
instruction at the beginning of the hypercall page. Since hypercalls are
made with an indirect call to the hypercall page, all hypercall attempts
fail with an exception and Linux panics.
A Hyper-V fix is in progress to add ENDBR64. But guard against the Linux
panic by clearing X86_FEATURE_IBT if the hypercall page doesn't start
with ENDBR. The VM will boot and run without IBT.
If future Linux 32-bit kernels were to support IBT, additional hypercall
page hackery would be needed to make IBT work for such kernels in a
Hyper-V VM.
CVE 정보
EPSS
EPSS는 취약점이 악용될 가능성을 예측하는 점수 모델입니다.
EPSS 점수
EPSS 모델은 0과 1(0~100%) 사이의 확률 점수를 생성합니다. 점수가 높을수록 취약점이 악용될 가능성이 높습니다.
날짜
EPSS V0
EPSS V1
EPSS V2 (> 2022-02-04)
EPSS V3 (> 2025-03-07)
EPSS V4 (> 2025-03-17)
2025-12-31
–
–
–
–
0.02%
2026-01-05
–
–
–
–
0.02%
2026-02-22
–
–
–
–
0.02%
2026-03-08
–
–
–
–
0.03%
2026-03-22
–
–
–
–
0.03%
2026-05-10
–
–
–
–
0.03%
2026-05-17
–
–
–
–
0.03%
2026-05-31
–
–
–
–
0.02%
2026-06-14
–
–
–
–
0.02%
EPSS 백분위수
백분위수는 EPSS 점수에 따라 CVE의 순위를 매기는 데 사용됩니다. 예를 들어 EPSS 점수 기준 95번째 백분위수의 CVE는 다른 CVE의 95%보다 악용될 가능성이 높습니다.