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Linux CVE-2026-98639

| EUVDEUVD-2026-103553
2026-10-18 Linux GHSA-2qhr-3xrg-mw89
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Monitor Track and reassess. Why: No CVSS yet + weak signal (CWE or non-zero EPSS).
Patch available 0.2% exploitation probability (EPSS)

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AnalysisCVE.org

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.

Affected VersionsENISA

Linux patch: 7.3-rc5
Linux patch: 0
Linux 6.13
Linux patch: 6.18.55
Linux d466c19cead5904d4d5d92adb2b213b411d3b849 <b3d346838ec65fac7fd83f5dbcedd13cadfffddb
Linux patch: 7.2.9
Linux d466c19cead5904d4d5d92adb2b213b411d3b849 <d6de766d8d26d71b714f548192099112def50a9c
Linux d466c19cead5904d4d5d92adb2b213b411d3b849 <6da466502621381fa88a6684290923d25c559266

Affected Packages

euvd linux no fix

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 1 package in euvd

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Lifecycle Timeline

2
Patch available
Oct 18, 2026 - 16:02 EUVD
CVE Published
Oct 18, 2026 - 15:20 cve.org
UNKNOWN (no severity yet)

Threat Intelligence Overview

EPSS Score
0.2%
Top 95% exploitable
Data Quality
3 sources
Confidence: Low

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity Not scored yet
CISA KEV No
Public POC No
EPSS 0.2%
Patch available Yes
Active threat No
Deciding rule
No CVSS yet + weak signal (CWE or non-zero EPSS)
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

Attack Technique

Information disclosure occurs when an application unintentionally exposes sensitive data that aids attackers in reconnaissance or directly compromises security.

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