Linux hwe edge: In the Linux kernel, the following vulnerability has been resolved: KVM: SEV: Drop WARN on large size for KVM_MEMORY_ENCRYPT_REG_REGION Drop the… (CVE-2026-31590)
A medium severity vulnerability (CVE-2026-31590) in the Linux kernel's KVM SEV subsystem was addressed. The issue involved a WARN triggered on large size values for KVM_MEMORY_ENCRYPT_REG_REGION, which could be trivially triggered from userspace due to improper handling of 64-bit address and size values. This flaw was fixed in Linux kernel versions 5.15.0-186.196 and later. The vulnerability does not impact confidentiality or integrity but can cause denial of service (system crash). A patch is available and should be applied. The vendor advisory from Ubuntu confirms the fix and recommends updating to the specified patched kernel versions.
AI Analysis
Technical Summary
The vulnerability CVE-2026-31590 in the Linux kernel's KVM SEV subsystem was caused by a WARN triggered in sev_pin_memory() when the number of pages (npages) overflows an integer due to large size values passed in KVM_MEMORY_ENCRYPT_REG_REGION ioctl calls. The checks for address and size were ineffective because both are 64-bit values and cannot exceed ULONG_MAX on SEV 64-bit systems. This flaw could be trivially triggered from userspace, potentially causing a denial of service by crashing the kernel. The issue has been resolved in Linux kernel versions 5.15.0-186.196 and later. The Ubuntu vendor advisory confirms the availability of patches and recommends updating to the fixed kernel versions.
Potential Impact
The vulnerability allows a local attacker to trigger a kernel WARN condition by passing large size values in the KVM_MEMORY_ENCRYPT_REG_REGION ioctl, leading to a denial of service (system crash). There is no impact on confidentiality or integrity. No known exploits are reported in the wild.
Mitigation Recommendations
A patch is available and has been released in Linux kernel versions 5.15.0-186.196 and later. Users should update their Linux kernel to the fixed versions as provided by their vendor, such as the Ubuntu kernel packages listed in the advisory. After updating, a system reboot is required. Due to ABI changes, recompilation and reinstallation of third-party kernel modules may be necessary. Follow vendor instructions for updating and rebuilding kernel modules.
Linux hwe edge: In the Linux kernel, the following vulnerability has been resolved: KVM: SEV: Drop WARN on large size for KVM_MEMORY_ENCRYPT_REG_REGION Drop the… (CVE-2026-31590)
Description
A medium severity vulnerability (CVE-2026-31590) in the Linux kernel's KVM SEV subsystem was addressed. The issue involved a WARN triggered on large size values for KVM_MEMORY_ENCRYPT_REG_REGION, which could be trivially triggered from userspace due to improper handling of 64-bit address and size values. This flaw was fixed in Linux kernel versions 5.15.0-186.196 and later. The vulnerability does not impact confidentiality or integrity but can cause denial of service (system crash). A patch is available and should be applied. The vendor advisory from Ubuntu confirms the fix and recommends updating to the specified patched kernel versions.
CVSS v3.1
Score 5.5medium
Affected software
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protected]~18.04.1?arch=source&distro=bionicpkg:deb/ubuntu/[email protected]~20.04.1?arch=source&distro=focalpkg:deb/ubuntu/[email protected]~20.04.1?arch=source&distro=focalpkg:deb/ubuntu/[email protected]~20.04.1?arch=source&distro=esm-infra/focalpkg:deb/ubuntu/[email protected]~20.04.1?arch=source&distro=focalpkg:deb/ubuntu/[email protected]~20.04.2?arch=source&distro=focalpkg:deb/ubuntu/[email protected]~20.04.1?arch=source&distro=focalpkg:deb/ubuntu/[email protected]~20.04.1?arch=source&distro=esm-infra/focalpkg:deb/ubuntu/[email protected]~20.04.1?arch=source&distro=focalpkg:deb/ubuntu/[email protected]+cvm1.1?arch=source&distro=focalpkg:deb/ubuntu/[email protected]~20.04.1?arch=source&distro=esm-infra/focalpkg:deb/ubuntu/[email protected]~20.04.3?arch=source&distro=focalpkg:deb/ubuntu/[email protected]~20.04.1?arch=source&distro=focalpkg:deb/ubuntu/[email protected]~20.04.1?arch=source&distro=esm-infra/focalpkg:deb/ubuntu/[email 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protected]?arch=source&distro=questingpkg:deb/ubuntu/[email protected]?arch=source&distro=questingpkg:deb/ubuntu/[email protected]?arch=source&distro=questingpkg:deb/ubuntu/[email protected]?arch=source&distro=questingpkg:deb/ubuntu/[email protected]?arch=source&distro=questingpkg:deb/ubuntu/[email protected]?arch=source&distro=questingpkg:deb/ubuntu/[email protected]?arch=source&distro=questingpkg:deb/ubuntu/[email protected]?arch=source&distro=questingpkg:deb/ubuntu/[email protected]?arch=source&distro=questingpkg:deb/ubuntu/[email protected]?arch=source&distro=resolutepkg:deb/ubuntu/[email protected]?arch=source&distro=resolutepkg:deb/ubuntu/[email protected]?arch=source&distro=resolutepkg:deb/ubuntu/[email protected]?arch=source&distro=resolutepkg:deb/ubuntu/[email protected]?arch=source&distro=resolutepkg:deb/ubuntu/[email protected]?arch=source&distro=resolutepkg:deb/ubuntu/[email protected]?arch=source&distro=resolutepkg:deb/ubuntu/[email protected]?arch=source&distro=resolutepkg:deb/ubuntu/[email protected]?arch=source&distro=resolutepkg:deb/ubuntu/[email protected]?arch=source&distro=resolutepkg:deb/ubuntu/[email protected]?arch=source&distro=resoluteRun on your own infrastructure? 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AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The vulnerability CVE-2026-31590 in the Linux kernel's KVM SEV subsystem was caused by a WARN triggered in sev_pin_memory() when the number of pages (npages) overflows an integer due to large size values passed in KVM_MEMORY_ENCRYPT_REG_REGION ioctl calls. The checks for address and size were ineffective because both are 64-bit values and cannot exceed ULONG_MAX on SEV 64-bit systems. This flaw could be trivially triggered from userspace, potentially causing a denial of service by crashing the kernel. The issue has been resolved in Linux kernel versions 5.15.0-186.196 and later. The Ubuntu vendor advisory confirms the availability of patches and recommends updating to the fixed kernel versions.
Potential Impact
The vulnerability allows a local attacker to trigger a kernel WARN condition by passing large size values in the KVM_MEMORY_ENCRYPT_REG_REGION ioctl, leading to a denial of service (system crash). There is no impact on confidentiality or integrity. No known exploits are reported in the wild.
Mitigation Recommendations
A patch is available and has been released in Linux kernel versions 5.15.0-186.196 and later. Users should update their Linux kernel to the fixed versions as provided by their vendor, such as the Ubuntu kernel packages listed in the advisory. After updating, a system reboot is required. Due to ABI changes, recompilation and reinstallation of third-party kernel modules may be necessary. Follow vendor instructions for updating and rebuilding kernel modules.
Technical Details
- Gcve Source
- db.gcve.eu
- Osv Id
- UBUNTU-CVE-2026-31590
- Osv Schema Version
- 1.7.0
- Ecosystems
- ["Ubuntu:16.04:LTS","Ubuntu:18.04:LTS","Ubuntu:20.04:LTS","Ubuntu:Pro:20.04:LTS","Ubuntu:22.04:LTS","Ubuntu:Nvidia-BlueField:22.04:LTS","Ubuntu:Pro:FIPS-preview:22.04:LTS","Ubuntu:Pro:FIPS-updates:22.04:LTS","Ubuntu:Pro:Realtime:22.04:LTS","Ubuntu:24.04:LTS","Ubuntu:Nvidia-BlueField:24.04:LTS","Ubuntu:Pro:FIPS-updates:24.04:LTS","Ubuntu:Pro:Realtime:24.04:LTS","Ubuntu:25.10","Ubuntu:26.04:LTS"]
- Cvss Version
- 3.1
Threat ID: 6a5b61f42d1edb114c887ec8
Added to database: 07/18/2026, 11:22:28 UTC
Last enriched: 08/22/2026, 19:35:34 UTC
Last updated: 09/11/2026, 07:31:52 UTC
Views: 26
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