CVE-2026-53360
Description
A flaw was found in the Linux kernel's KVM (Kernel-based Virtual Machine) subsystem, specifically within the SEV (Secure Encrypted Virtualization) feature. A malicious guest operating system utilizing SEV-SNP (Secure Nested Paging) can exploit an out-of-bounds write vulnerability due to improper validation of guest-controlled input during Guest-Host Communication Block (GHCB) operations. This allows the guest to read and write beyond allocated memory regions, leading to host kernel heap memory corruption and disclosure of sensitive heap layout information. This could enable a malicious guest to escalate privileges on the host system.
Statement
Red Hat Enterprise Linux 6 and 7 are not affected by this flaw, as they did not include support for KVM AMD Secure Encrypted Virtualization (SEV). AMD SEV is currently provided as a Technology Preview in RHEL 8. AMD SEV-SNP (Secure Nested Paging) is currently provided as a Technology Preview in RHEL 9 and 10. Therefore, SEV-SNP is not supported for production use across all versions of Red Hat Enterprise Linux.
Mitigation
If confidential VMs are not in use, this vulnerability can be mitigated by disabling SEV-SNP support on the host, removing the attack surface entirely. Create a file in `/etc/modprobe.d/` with a descriptive name, such as `cve-2026-53360-mitigation.conf`. In that file, disable SEV-SNP for the `kvm_amd` kernel module:
options kvm_amd sev_snp=0
To validate, read the file `/sys/module/kvm_amd/parameters/sev_snp`. This file should read `N` to indicate that the feature is disabled.
If SEV-SNP cannot be disabled, run SEV-SNP hosts on isolated environments and restrict the ability to create SNP-enabled VMs to trusted tenants/administrators only.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 8.8 | N/A | 8.8 |
| Attack Vector | Local | N/A | Local |
| Attack Complexity | Low | N/A | Low |
| Privileges Required | Low | N/A | Low |
| User Interaction | None | N/A | None |
| Scope | Changed | N/A | Changed |
| Confidentiality | High | N/A | High |
| Integrity Impact | High | N/A | High |
| Availability Impact | High | N/A | High |
Vector
Red Hat: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
cve.org: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
Understanding the Weakness (CWE)
Integrity
Technical Impact: Modify Memory; Execute Unauthorized Code or Commands
Write operations could cause memory corruption. In some cases, an adversary can modify control data such as return addresses in order to execute unexpected code.
Availability
Technical Impact: DoS: Crash, Exit, or Restart
Attempting to access out-of-range, invalid, or unauthorized memory could cause the product to crash.
Other
Technical Impact: Unexpected State
Subsequent write operations can produce undefined or unexpected results.
Frequently Asked Questions
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