CVE-2026-89981
Received
Received - Intake
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Vulnerability report for CVE-2026-89981, including description, CVSS score, EPSS score, affected products, exploitability, helpful resources, and attack-flow context.
Publication date: 2026-09-16
Last updated on: 2026-09-16
Assigner: kernel.org
Description
Description
In the Linux kernel, the following vulnerability has been resolved:
arm64: Don't read GMID_EL1 when MTE is disabled
__cpuinfo_store_cpu() gates the GMID_EL1 read on the raw
ID_AA64PFR1_EL1, so it reads the register even when the kernel has
disabled MTE (CONFIG_ARM64_MTE=n or arm64.nomte). KVM sets HCR_EL2.TID5
in that case, and pKVM injects an UNDEF the host cannot handle:
Internal error: Oops - Undefined instruction: 0000000002000000 [#1] SMP
pc : __cpuinfo_store_cpu+0xf4/0x264
Kernel panic - not syncing: Attempted to kill the idle task!
Only pKVM reaches it, and only after a CPU is offlined and brought back
online: its CPU_ON relay sets the host HCR before the CPU enters EL1,
while plain nVHE sets it at CPUHP_AP_KVM_ONLINE.
Gate the read on the CPU's own ID_AA64PFR1_EL1 with the command-line
override applied, and on CONFIG_ARM64_MTE, which no register reflects.
The boot CPU stores its registers before init_cpu_features() strips an
unsafe override, so clamp against the hardware value here too.
CVSS Scores
EPSS Scores
| Probability: | |
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Meta Information
Affected Vendors & Products
Currently, no data is known.
Helpful Resources
Exploitability
CWE
KEV
| CWE ID | Description |
|---|---|
| CWE-UNKNOWN |
