High [CVE-2026-63938] Check PSC request indices against the actual size of the buffer
This high-severity Red Hat Linux advisory covers CVE-2026-63938 affecting Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 9, Red Hat package: kernel.
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Summary
In the Linux kernel, the following vulnerability has been resolved: KVM: SEV: Check PSC request indices against the actual size of the buffer When processing Page State Change (PSC) requests, validate the PSC buffer against the effective size of the scratch area, which could be less than the maximum size if the guest provided a pointer that isn't exactly at the start of the GHCB shared buffer.
A flaw was found in the Linux kernel's Kernel-based Virtual Machine (KVM) Secure Encrypted Virtualization (SEV) feature. This can occur if a guest operating system provides a pointer that is not precisely at the start of the Guest Hypervisor Communication Block (GHCB) shared buffer, potentially leading to out-of-bounds memory access.
This vulnerability could allow a malicious guest to cause a denial of service on the host system. Red Hat severity: Moderate — CVSS 7 (CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H).
Weakness: CWE-1285. Affected Red Hat products: Red Hat Enterprise Linux 10; Red Hat Enterprise Linux 9.
Red Hat does not currently list a fixing RHSA for this CVE.
Affected products named by the advisory: Red Hat package: kernel.
Affected versions
No affected-version range was extracted from the source record. The vendor advisory is authoritative. Check it before change work.
Official advisory · medium-confidence parse· fetched 7 days ago·verify at source
Fixed versions
No fixed release is recorded yet. That does not prove no patch exists. Confirm against the vendor advisory.
Official advisory · medium-confidence parse· fetched 7 days ago·verify at source
Mitigation
The source record does not include mitigation steps. That does not mean no fix exists. Read the vendor advisory below for the authoritative guidance.
Official advisory · medium-confidence parse· fetched 7 days ago·verify at source
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