Linux Kernel up to 6.12.109/6.18.50/7.2.4/7.3-rc1 KVM kvm_arch_prepare_memory_region buffer overflow

CVSS Meta Temp Score
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Current Exploit Price (≈)
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CTI Interest Score
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9.5$5k-$25k0.45

Summaryinfo

A vulnerability was found in Linux Kernel up to 6.12.109/6.18.50/7.2.4/7.3-rc1 and classified as very critical. The affected element is the function kvm_arch_prepare_memory_region of the component KVM. Such manipulation leads to buffer overflow. This vulnerability is uniquely identified as CVE-2026-89908. The attack can be launched remotely. No exploit exists. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability was found in Linux Kernel up to 6.12.109/6.18.50/7.2.4/7.3-rc1 and classified as very critical. Affected by this issue is the function kvm_arch_prepare_memory_region of the component KVM. The manipulation with an unknown input leads to a buffer overflow vulnerability. Using CWE to declare the problem leads to CWE-120. The product copies an input buffer to an output buffer without verifying that the size of the input buffer is less than the size of the output buffer, leading to a buffer overflow. Impacted is confidentiality, integrity, and availability. CVE summarizes:

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.

The advisory is shared for download at git.kernel.org. This vulnerability is handled as CVE-2026-89908 since 09/11/2026. The exploitation is known to be easy. The attack may be launched remotely. There are known technical details, but no exploit is available. The current price for an exploit might be approx. USD $5k-$25k (estimation calculated on 09/16/2026).

Upgrading to version 6.12.110, 6.18.51, 7.2.5 or 7.3-rc2 eliminates this vulnerability. Applying the patch 7c6df65b53846cd7a9a1c81c6ddb42fdc08603e8/4e4dbc341b1581dc512b85d98b768373b0398366/bc7a6849b4395f45a602db91b0fb2fb2e9ed4bba/27a9bfee3bbcb3cabb77797354f07e0e44e49831 is able to eliminate this problem. The best possible mitigation is suggested to be upgrading to the latest version.

VulDB is the best source for vulnerability data and more expert information about this specific topic.

Productinfo

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Version

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CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 9.9
VulDB Meta Temp Score: 9.5

VulDB Base Score: 9.9
VulDB Temp Score: 9.5
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Buffer overflow
CWE: CWE-120 / CWE-119
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 6.12.110/6.18.51/7.2.5/7.3-rc2
Patch: 7c6df65b53846cd7a9a1c81c6ddb42fdc08603e8/4e4dbc341b1581dc512b85d98b768373b0398366/bc7a6849b4395f45a602db91b0fb2fb2e9ed4bba/27a9bfee3bbcb3cabb77797354f07e0e44e49831

Timelineinfo

09/11/2026 CVE reserved
09/16/2026 +5 days Advisory disclosed
09/16/2026 +0 days VulDB entry created
09/16/2026 +0 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2026-89908 (🔒)
GCVE (CVE): GCVE-0-2026-89908
GCVE (VulDB): GCVE-100-405752

Entryinfo

Created: 09/16/2026 14:31
Changes: 09/16/2026 14:31 (59)
Complete: 🔍
Cache ID: 216::103

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