{"cve":"CVE-2026-89915","nvd":{"published":"2026-09-16T11:17:00.553","modified":"2026-10-19T09:18:36.977","status":"Received","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nKVM: arm64: Remove VM-wide VNCR mapping counter\n\nThe global VNCR mapping counter is used to decide whether an L1\nprovided VNCR page is mapped in L0 on any CPU at the point of\ndealing with a TLB invalidation. It is incremented when a mapping\nis made in the fixmap, and decremented when unmapped.\n\nAs it turns out, this tracking has several flaws:\n\n- we are trying to invalidate TLBs, and the mapping is only an\n  opportunistic consequence of the TLB. Checking this counter to\n  decide whether a TLB needs to be invalidated may result in missed\n  invalidations.\n\n- an L1 vcpu invalidating its own TLB (a very likely case) will not\n  succeed in invalidating the VNCR pseudo TLB because that page is\n  not mapped in L0 at this stage.\n\nGiven that this tracking fails at delivering the minimum guarantees\nthat are required and is only a performance optimisation, remove it\ncompletely.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H","score":9.3},"cwes":[],"references":["https://git.kernel.org/stable/c/5453b85c7ebb605febac3df42021f9471663f051","https://git.kernel.org/stable/c/87c2bbf189829dce4aaada8f82e3d54ccc037976","https://git.kernel.org/stable/c/c55bc773b6e814406658fae7dc5c15f639ed816e"],"products":[],"source":"nvd","synced_at":"2026-10-19T22:54:41.405518556+00:00"},"epss":{"cve":"CVE-2026-89915","score":0.00194,"percentile":0.08947,"date":"2026-10-25"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}