CVE-2026-89915KVM: arm64: Remove VM-wide VNCR mapping counter
Updated under an hour ago ()
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No exploitation reported and no EPSS estimate yet.
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In the Linux kernel, the following vulnerability has been resolved: KVM: arm64: Remove VM-wide VNCR mapping counter The global VNCR mapping counter is used to decide whether an L1 provided VNCR page is mapped in L0 on any CPU at the point of dealing with a TLB invalidation. It is incremented when a mapping is made in the fixmap, and decremented when unmapped. As it turns out, this tracking has several flaws: - we are trying to invalidate TLBs, and the mapping is only an opportunistic consequence of the TLB. Checking this counter to decide whether a TLB needs to be invalidated may result in missed invalidations. - an L1 vcpu invalidating its own TLB (a very likely case) will not succeed in invalidating the VNCR pseudo TLB because that page is not mapped in L0 at this stage. Given that this tracking fails at delivering the minimum guarantees that are required and is only a performance optimisation, remove it completely.
- CVSS
- 9.3 CRITICAL (v3.1, CNA)CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
- Weakness (CWE)
- Not given
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- Linux
- NVD analysis
- Received
- Record last updated
- Oct 19, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
Linux Linux linux:linux (from the name) | from 4ffa72ad8f37e73bbb6c0baa88557bcb4fd39929 before 5453b85c7ebb605febac3df42021f9471663f051; from 4ffa72ad8f37e73bbb6c0baa88557bcb4fd39929 before 87c2bbf189829dce4aaada8f82e3d54ccc037976; from 4ffa72ad8f37e73bbb6c0baa88557bcb4fd39929 before c55bc773b6e814406658fae7dc5c15f639ed816e | CNA record |
References
- https://git.kernel.org/stable/c/5453b85c7ebb605febac3df42021f9471663f051
- https://git.kernel.org/stable/c/87c2bbf189829dce4aaada8f82e3d54ccc037976
- https://git.kernel.org/stable/c/c55bc773b6e814406658fae7dc5c15f639ed816e
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.