VulnerabilityPublished 18 Oct 2026

CVE-2026-98637: Linux kernel · KVM: arm64: Do not clear VM-wide SVE feature on vCPU init failure

Source GCVE Database

Authoritative record:CVE-2026-98637· Medium

Not known to be exploited · fixed in f0cd8ffae092cc1b9d7cfa9188ed5a88a374adcb : update Linux kernel when convenient.

Data as of 26 Oct 2026, 17:16 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 f0cd8ffae092cc1b9d7cfa9188ed5a88a374adcb, bd46b41f412fb81c50bac1a0929ec31320f3a807, a1b3c788ad31837e348075e93dbba3f447492776

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-j9wj-wgv2-phcm

What to do

Upgrade Linux kernel to f0cd8ffae092cc1b9d7cfa9188ed5a88a374adcb, bd46b41f412fb81c50bac1a0929ec31320f3a807 or a1b3c788ad31837e348075e93dbba3f447492776.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ 5db1bef933427aa467ad89c7b695a84a6b4afe16, < f0cd8ffae092cc1b9d7cfa9188ed5a88a374adcb	Fixed in f0cd8ffae092cc1b9d7cfa9188ed5a88a374adcb
LinuxLinux	Affected ≥ 5db1bef933427aa467ad89c7b695a84a6b4afe16, < bd46b41f412fb81c50bac1a0929ec31320f3a807	Fixed in bd46b41f412fb81c50bac1a0929ec31320f3a807
LinuxLinux	Affected ≥ 5db1bef933427aa467ad89c7b695a84a6b4afe16, < a1b3c788ad31837e348075e93dbba3f447492776	Fixed in a1b3c788ad31837e348075e93dbba3f447492776
LinuxLinux	Affected =6.16	Fixed in–

AI-suggested

A fix has been implemented in the Linux kernel to address this issue by ensuring that on vCPU initialization failure, the VM-wide SVE feature flags are not cleared improperly. Users should update to the fixed Linux kernel version once available. Patch status is not explicitly confirmed in the provided data; therefore, check the official Linux kernel advisories for the specific patch and remediation guidance.

Description

A vulnerability in the Linux kernel's KVM arm64 implementation related to the handling of the Scalable Vector Extension (SVE) feature on virtual CPU initialization failure has been resolved. The issue involved improper clearing of VM-wide SVE feature flags, causing subsequent vCPUs to skip SVE setup and potentially leading to a NULL pointer dereference during the guest's first floating-point access. The fix ensures that the error is returned without modifying the vcpu_features state.

Impact

The vulnerability can lead to improper handling of the SVE feature state in virtual CPUs, potentially causing a NULL pointer dereference or crash during guest floating-point operations. This could affect the stability and reliability of virtual machines using KVM on arm64 architectures with SVE enabled. There is no indication of code execution or privilege escalation from the provided data.

Summary

The vulnerability in the Linux kernel KVM arm64 code occurs because the function pkvm_vcpu_init_sve() clears the KVM_ARM_VCPU_SVE flag in kvm->arch.vcpu_features when it fails, but the vcpu_has_sve() function checks KVM_ARCH_FLAG_GUEST_HAS_SVE, which remains set. This mismatch causes later virtual CPUs on the same VM to skip SVE setup and register with a NULL sve_state. When the guest performs its first floating-point operation, the NULL sve_state is passed to sve_load_state(), potentially causing a fault. The patch corrects this by returning the error without altering vcpu_features, preventing inconsistent state.

References

Community reviews

Loading reviews…