CVE-2026-64561
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…
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (0.35%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
Description
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.
- CVSS 3.1
- 8.8 HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
- EPSS
- 0.35% probability · 28th percentile
- CISA KEV
- Not listed
- Source
- 416baaa9-dc9f-4396-8d5f-8c081fb06d67
References
- https://git.kernel.org/stable/c/0026dbb7de8ea76e97d6edf42fc3cc084564e2bf
- https://git.kernel.org/stable/c/2abd5287f08319fa35764566b15c6e22cb1068db
- https://git.kernel.org/stable/c/35e77467610c4a37cb0ff54ee56b85f73b1f5700
- https://git.kernel.org/stable/c/62ef67af1878fa2cd066642f2f59e33ade95f637
- https://git.kernel.org/stable/c/65c4f7a1028cf01a93a2762d679c289810ede990
- https://git.kernel.org/stable/c/bce0d3c26e2c761a4bf43c8949f333fc7374eb2d
- https://git.kernel.org/stable/c/f3477a6a4164f15287444eda685b5f6405dbd1e5
- https://github.com/V4bel/Zapscape
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.