CVE-2026-63941
KVM on ARM64: L2 guest can bypass ZCR_EL2 caps to access larger SVE VLs.
Is CVE-2026-63941 being exploited?
Not confirmed. CVE-2026-63941 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 0.15% probability of exploitation in the next 30 days.
How severe is CVE-2026-63941?
CVE-2026-63941 is rated High with a CVSS score of 8.8. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2026-63941?
Yes. A fix has been recorded for CVE-2026-63941. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-63941 affect?
CVE-2026-63941 affects Linux kernel (KVM) on arm64, Nested virtualization (L2) with SVE, ARM64 cloud/servers running KVM. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-63941?
Apply vendor kernel/KVM patches; disable nested virtualization or restrict SVE until patched.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
A nested L2 guest can program ZCR_EL1 to obtain larger SVE VLs than allowed, enabling unauthorized register access and potential guest-to-hypervisor data leakage or escalation.
Patch when possible
- affected>= b3d29a8230998b36afecf494b199211d26052785 and < 742a9b5ccd8c46caf983ca90c94f855466968e34
- affected>= b3d29a8230998b36afecf494b199211d26052785 and < 83726330748981372bde86ed5411d7b306612991
- affected6.11
As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.