VulnerabilityPublished 23 Oct 2026

CVE-2026-98928: Linux kernel · KVM: arm64: Derive GUEST_HAS_SVE from the SVE feature bit at EL2

Source GCVE Database

Authoritative record:CVE-2026-98928

Not known to be exploited · fixed in 7b5e99d286747b6b5b583b8efcd06bdbdd94b229 : 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 7b5e99d286747b6b5b583b8efcd06bdbdd94b229, 4f16c5fc8dc4c5596e3777ab9f449a54e3f85fd5, 4efda204087145d40a84344edec7e9d3885ad3ab

Exploitation evidence

Disclosed: evidence found.
CVE published 23 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-vj8p-cgf2-cww7

What to do

Upgrade Linux kernel to 7b5e99d286747b6b5b583b8efcd06bdbdd94b229, 4f16c5fc8dc4c5596e3777ab9f449a54e3f85fd5 or 4efda204087145d40a84344edec7e9d3885ad3ab.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ 41d6028e28bd474298ff10409c292ec46cf43a90, < 7b5e99d286747b6b5b583b8efcd06bdbdd94b229	Fixed in 7b5e99d286747b6b5b583b8efcd06bdbdd94b229
LinuxLinux	Affected ≥ 41d6028e28bd474298ff10409c292ec46cf43a90, < 4f16c5fc8dc4c5596e3777ab9f449a54e3f85fd5	Fixed in 4f16c5fc8dc4c5596e3777ab9f449a54e3f85fd5
LinuxLinux	Affected ≥ 41d6028e28bd474298ff10409c292ec46cf43a90, < 4efda204087145d40a84344edec7e9d3885ad3ab	Fixed in 4efda204087145d40a84344edec7e9d3885ad3ab
LinuxLinux	Affected =6.14	Fixed in–

AI-suggested

A fix for this vulnerability has been implemented in the Linux kernel. Users should update to a kernel version that includes this patch to ensure correct handling of the GUEST_HAS_SVE flag and SVE state in arm64 KVM guests.

Description

A vulnerability in the Linux kernel's KVM module for arm64 architecture related to the handling of the Scalable Vector Extension (SVE) feature bit at EL2 has been resolved. The issue involved inconsistent derivation and use of the GUEST_HAS_SVE flag, which could lead to a virtual CPU (vCPU) having a NULL SVE state. This inconsistency arose because the flag was taken separately from the host, but the actual feature bit was tested differently, potentially causing improper SVE state loading in guests. The fix derives the GUEST_HAS_SVE flag directly from the SVE feature bit and removes redundant code related to protected VMs, which do not allow SVE.

Impact

The vulnerability could cause incorrect handling of the SVE state in virtual CPUs on arm64 KVM guests, potentially leading to inconsistent or invalid SVE state during context switches. This may affect the stability or correctness of virtual machines using SVE features. However, no known exploits in the wild have been reported.

Summary

The Linux kernel's KVM arm64 implementation had a vulnerability where the GUEST_HAS_SVE flag was inconsistently derived from the host's SVE feature bit at EL2. The function pkvm_init_features_from_host() separately took the flag and the SVE feature bit, but pkvm_vcpu_init_sve() tested the bit while vcpu_has_sve() read the flag, leading to a mismatch. This could result in a vCPU with a NULL sve_state, causing the world switch to load the guest's SVE state incorrectly. The patch fixes this by deriving the GUEST_HAS_SVE flag directly from the SVE feature bit and removing dead code related to protected VMs, which are not allowed to use SVE.

References

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