TI-2026-75767 Aliases CVE-2026-98639 GHSA-2qhr-3xrg-mw89

Wrong TLB flush ranges in Linux KVM RISC-V nested fence entries

LOW 22Published 2026-10-18 · Updated 2026-10-19

Key facts

Attack vector: —
Privileges required: —
User interaction: —
Attack complexity: —
Impact type: —
Confidentiality · integrity · availability: —
Fix status: Fixed

No CVSS vector from any source. Fix status from CNA.

Summary

The Linux kernel from 6.13 contains a flaw in the KVM RISC-V nested HFENCE entry update performed by __kvm_riscv_nacl_hfence(). The function writes the Config word before the Page_Number and Page_Count words, so the SBI implementation or NACL hardware can observe a pending entry with stale values left from the entry's previous use. This results in incorrect TLB flush ranges.

Written with Claude Haiku 5.5 from the sources below · 2026-11-06

Description from the CNA

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.

Why it matters now

EPSS 0.00166 5th percentileScored 2026-11-07

Fix Fixed Linux (Linux): 6.18.55, 7.2.9, 7.3

SSVC decision points

Not available: CISA has not published SSVC decision points for this record.

Affected products

Vendor	Product	Affected versions	Fixed in	Status	Source
Linux	Linux	6.13 and later	6.18.55, 7.2.9, 7.3	Patch available	CNA

Linux VendorLinux Affected 6.13 and later Fixed in 6.18.55, 7.2.9, 7.3 Patch available CNA

CPE names Threatist (inferred) · 1

Inferred from how NVD named this product before; not given by a source.

CPE	Versions	Role	Vendor
cpe:2.3:o:linux:linux_kernel::::::::	—	—	Linux

cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* Versions — — ·Linux

Remediation

Upgrade the Linux kernel to 6.18.55, 7.2.9 or 7.3, which contain the fix.

Written with Claude Haiku 5.5 from the sources below · 2026-11-06

Fix · CNA Linux (Linux) Fixed in 6.18.55, 7.2.9, 7.3

Vendor assessments

Red Hat

Red Hat rating: Important. Red Hat's page for this CVE →

Not affected: 7 products

Red Hat Enterprise Linux 10
Red Hat Enterprise Linux 6
Red Hat Enterprise Linux 7
Red Hat Enterprise Linux 8
Red Hat Enterprise Linux 9
Red Hat OpenShift Container Platform 4
Red Hat OpenShift Container Platform 5

Timeline

2026-10-18 Threatist record created from CVE-2026-98639
2026-10-18 Alias added: GHSA-2qhr-3xrg-mw89
2026-10-19 Fix available: Linux/[email protected] · CNA
2026-10-21 Affected versions changed · Red Hat
2026-10-21 CVSS score added · Red Hat
2026-10-22 Affected versions changed · Red Hat
2026-11-05 Affected versions changed · Red Hat

References

Other 3

TI-2025-26358 tls: fix handling of zero-length records on the rx_list KEVCVSS 3.1CRITICAL 9.8
TI-2026-38352 netfilter: bridge: make ebt_snat ARP rewrite writable KEVCVSS 3.1HIGH 8.8
TI-2021-02452 Incorrect authorization in Ubuntu linux kernel KEVCVSS 3.1HIGH 8.8
TI-2013-05264 The (1) get_user and (2) put_user API functions in the Linux kernel before 3.5.5 on the… KEVCVSS 3.1HIGH 8.8
TI-2022-00125 Integer overflow in kernel KEVCVSS 3.1HIGH 8.4
TI-2013-01864 The perf_swevent_init function in kernel/events/core.c in the Linux kernel before 3.8.9… KEVCVSS 3.1HIGH 8.4

See all 21741 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences