CVE-2026-89917 Affecting kernel6.18-debuginfo package, versions <1:6.18.54-121.166.amzn2023
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-AMZN2023-KERNEL618DEBUGINFO-21415615
- published22 Oct 2026
- disclosed16 Sept 2026
Introduced: 16 Sep 2026
CVE-2026-89917 (opens in a new tab)How to fix?
Upgrade Amazon-Linux:2023 kernel6.18-debuginfo to version 1:6.18.54-121.166.amzn2023 or higher.
This issue was patched in ALAS2023-2026-3192.
NVD Description
Note: Versions mentioned in the description apply only to the upstream kernel6.18-debuginfo package and not the kernel6.18-debuginfo package as distributed by Amazon-Linux.
See How to fix? for Amazon-Linux:2023 relevant fixed versions and status.
In the Linux kernel, the following vulnerability has been resolved:
KVM: arm64: Handle VNCR TLB invalidation race with vcpu_put() VNCR unmapping
While VNCR TLB invalidation always occurs under the MMU lock, vcpu_put() doesn't, while it unmaps the VNCR page.
The problem is that the invalidation evaluates vncr_tlb::cpu to decide whether an unmapping needs to take place (cpu != -1) before performing it. On the other hand, this_cpu_reset_vncr_fixmap() unconditionally unmaps if L1_VNCR_MAPPED is set.
These two obviously can race, with a TOCTOU pattern on the TLBI path, and a BUG_ON() on the vcpu_put() path. And the two can end-up calling vncr_fixmap(-1), with extra lethal effects.
Move the reset of vncr_tlb::cpu to -1 to a common function, and make this update atomic so that only a single thread can reset the field and perform the corresponding unmap. The vcpu_put() still need to unconditionally unmap the current VNCR to close another ugly race.
Finally, the assignment of vncr_tlb::cpu is moved to be kept in sync with the actual mapping, similar to L1_VNCR_MAPPED being set.