CVE-2026-98639

Unknown

Description

In the Linux kernel, the following vulnerability has been resolved: KVM: riscv: Fix NACL hfence entry update order The SBI v3.0 specification (section 15.1.2) requires a nested HFENCE entry to be populated as follows: 1) find an unused entry with Config.Pending == 0 2) update the Page_Number and Page_Count words 3) update the Config word with Config.Pending set __kvm_riscv_nacl_hfence() writes the Config word first, so the SBI implementation (or NACL hardware) can observe a pending entry with pnum/pcount values left over from the previous use of that entry, resulting in incorrect TLB flush ranges. Write pnum and pcount first and the Config word last. Since the consumer is an external agent on coherent shared memory, use WRITE_ONCE() to stop the compiler from reordering the stores and smp_wmb() to make the parameter words globally visible before the Pending bit is set.

SeverityUnknown
CVSS—
Exploit probability—
ProductLinux
PublishedOct 18, 2026
First seenOct 18, 2026

How to fix

Update
  • Linux Linuxd6de766d8d26d71b714f548192099112def50a9c, 6da466502621381fa88a6684290923d25c559266, b3d346838ec65fac7fd83f5dbcedd13cadfffddb or later

Affected products

ProductAffected versionsFixed in
Linux Linuxd466c19cead5904d4d5d92adb2b213b411d3b849 ≤ v < d6de766d8d26d71b714f548192099112def50a9c, d466c19cead5904d4d5d92adb2b213b411d3b849 ≤ v < 6da466502621381fa88a6684290923d25c559266, d466c19cead5904d4d5d92adb2b213b411d3b849 ≤ v < b3d346838ec65fac7fd83f5dbcedd13cadfffddb, 6.13d6de766d8d26d71b714f548192099112def50a9c, 6da466502621381fa88a6684290923d25c559266, b3d346838ec65fac7fd83f5dbcedd13cadfffddb

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