CVE Catalog

CVE-2026-64561

HighCVSS 8.8
Published: Updated: Translated: NVD NIST

Exploitation Probability (EPSS)

Low risk
0.35%

27th percentile - higher than 27% of all known CVEs

Summary

In the Linux kernel, KVM x86 has an issue where the check for invalid/obsolete root occurs before making MMU pages available for the shadow MMU. If reclaiming shadow pages zaps an in-use root, KVM may map memory into an invalid root, violating the invariant that invalid pages are never on the active MMU list. The fix moves the check after making MMU pages available.

Risk Assessment

The vulnerability may lead to kernel memory corruption, potentially causing system crash or privilege escalation in virtualized environments.

Recommendation

Update the Linux kernel to a patched version and test virtualized environments for stability.

Other vulnerabilities in Linux kernel

See all
Original NVD description (English source)

In the Linux kernel, the following vulnerability has been resolved: KVM: x86: Check for invalid/obsolete root *after* making MMU pages available Check for a "stale" page fault, i.e. for an invalid and/or obsolete root, after making MMU pages available for the shadow MMU. If reclaiming shadow pages zaps an in-use root, i.e. marks it invalid, then KVM will attempt to map memory into an invalid root. On its own, populating an invalid root is "fine", but because child shadow pages inherit their parent's role, any children created during the map/fetch will be created as invalid pages, thus violating KVM's invariant that invalid pages are never on the list of active MMU pages. Note, the underlying flaw has existed since KVM first started tracking invalid roots in 2008 (commit 2e53d63acba7, "KVM: MMU: ignore zapped root pagetables"), but the true badness only came along in 2020 (Linux 5.9) with the invariant that invalid shadow pages can't be on the list of active pages. Note #2, inheriting role.invalid when creating child shadow pages is also far from ideal; that flaw will be addressed separately.

Vulnerability data from NVD (NIST) · CISA KEV · EPSS