VulnerabilityPublished 18 Oct 2026

CVE-2026-98639: Linux kernel · KVM: riscv: Fix NACL hfence entry update order

Source GCVE Database

Authoritative record:CVE-2026-98639· Medium

Not known to be exploited · fixed in d6de766d8d26d71b714f548192099112def50a9c : update Linux kernel when convenient.

Data as of 26 Oct 2026, 14:05 UTC

Severity

Medium

Rated by Threat Radar · CVSS not yet scored by NVD

EPSS: 0.1% chance of exploitation in 30 days – higher than 5% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in d6de766d8d26d71b714f548192099112def50a9c, b3d346838ec65fac7fd83f5dbcedd13cadfffddb, 6da466502621381fa88a6684290923d25c559266

Exploitation evidence

Disclosed: evidence found.
CVE published 18 Oct 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

ghsa-2qhr-3xrg-mw89

What to do

Upgrade Linux kernel to d6de766d8d26d71b714f548192099112def50a9c, b3d346838ec65fac7fd83f5dbcedd13cadfffddb or 6da466502621381fa88a6684290923d25c559266.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ d466c19cead5904d4d5d92adb2b213b411d3b849, < d6de766d8d26d71b714f548192099112def50a9c	Fixed in d6de766d8d26d71b714f548192099112def50a9c
LinuxLinux	Affected ≥ d466c19cead5904d4d5d92adb2b213b411d3b849, < b3d346838ec65fac7fd83f5dbcedd13cadfffddb	Fixed in b3d346838ec65fac7fd83f5dbcedd13cadfffddb
LinuxLinux	Affected ≥ d466c19cead5904d4d5d92adb2b213b411d3b849, < 6da466502621381fa88a6684290923d25c559266	Fixed in 6da466502621381fa88a6684290923d25c559266
LinuxLinux	Affected =6.13	Fixed in–

AI-suggested

A fix has been implemented in the Linux kernel to correct the update order of the nested HFENCE entry in the KVM RISC-V code. Users should update to a Linux kernel version that includes this fix. Since no specific patch links or versions are provided, check the vendor or kernel release notes for the official fix. No additional mitigation is indicated.

Description

A vulnerability in the Linux kernel's KVM implementation for RISC-V was resolved by correcting the order of updates to the nested HFENCE (hfence) entry. The issue involved writing the Config word before updating the Page_Number and Page_Count, which could cause incorrect TLB flush ranges due to stale values being observed. The fix ensures the page number and count are written first, followed by the Config word, using memory barriers to prevent reordering.

References

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