CVE-2026-89908 Affecting linux-6.12 package, versions <6.12.111-1~deb12u1
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-DEBIAN12-LINUX612-20506332
- published5 Oct 2026
- disclosed16 Sept 2026
Introduced: 16 Sep 2026
NewCVE-2026-89908 (opens in a new tab)How to fix?
Upgrade Debian:12 linux-6.12 to version 6.12.111-1~deb12u1 or higher.
NVD Description
Note: Versions mentioned in the description apply only to the upstream linux-6.12 package and not the linux-6.12 package as distributed by Debian.
See How to fix? for Debian:12 relevant fixed versions and status.
In the Linux kernel, the following vulnerability has been resolved:
LoongArch: KVM: Preserve memslot arch flags on KVM_MR_FLAGS_ONLY
kvm_arch_prepare_memory_region() computes new->arch.flags, i.e. whether a memslot is KVM_MEM_HUGEPAGE_CAPABLE or KVM_MEM_HUGEPAGE_INCAPABLE, only for KVM_MR_CREATE and KVM_MR_MOVE, and returns early for every other change. But the generic code allocates a zeroed memslot for every change and never copies old->arch, so after a KVM_MR_FLAGS_ONLY update, e.g. toggling KVM_MEM_LOG_DIRTY_PAGES for live migration, the active memslot has arch.flags == 0.
With both flags clear, fault_supports_huge_mapping() falls through to the alignment check on the HVA range alone, which no longer verifies that the GPA and HVA have the same offset within a PMD. A memslot that was marked KVM_MEM_HUGEPAGE_INCAPABLE because of a GPA/HVA offset mismatch can then be mapped with PMD entries on read faults, and since kvm_map_page() aligns the gfn and the pfn independently, the guest ends up accessing the wrong host pages, exactly the "d -> f, e -> g" case described in the comment above the check.
Carry the arch flags over from the old memslot for KVM_MR_FLAGS_ONLY, as the GPA, HVA and size are guaranteed to be unchanged for that case.
References
- https://security-tracker.debian.org/tracker/CVE-2026-89908
- https://git.kernel.org/stable/c/27a9bfee3bbcb3cabb77797354f07e0e44e49831
- https://git.kernel.org/stable/c/4e4dbc341b1581dc512b85d98b768373b0398366
- https://git.kernel.org/stable/c/7c6df65b53846cd7a9a1c81c6ddb42fdc08603e8
- https://git.kernel.org/stable/c/bc7a6849b4395f45a602db91b0fb2fb2e9ed4bba