KVM: SEV: Compute the correct max length of the in-GHCB scratch area
In the Linux kernel, the following vulnerability has been resolved: KVM: SEV: Compute the correct max length of the in-GHCB scratch area When setting the length of the GHCB scratch area, and the area is in the GHCB shared buffer, set the effective length of the scratch area to the max possible size given the start of the guest-provided pointer, and the end of the shared buffer. The code was "fine" when first introduced, as KVM doesn't consult the length of the buffer when emulating MMIO, because the passed in @len always specifies the *max* size required. But for PSC requests, the incoming @len is just the minimum length (to process the header), and KVM needs to know the full size of the scratch area to avoid buffer overflows (spoiler alert). Opportunistically rename @len => @min_len to better reflect its role.
CVE-2026-63939
Primary source · Revision 1
Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.
Security context
Source reference: cve:CVE-2026-63939
Linux
Source reference: /containers/cna/affected/0/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Linux
Source reference: /containers/cna/affected/1/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Structured affected-version data
Original package identities and version rules from this source.
[
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "9b54e248d2644be71cb394eb85f31ad99e023a05",
"lessThan": "6ca9400d36005ffdca25f80186bea781c7e1dc4c",
"versionType": "git"
},
{
"status": "affected",
"version": "9b54e248d2644be71cb394eb85f31ad99e023a05",
"lessThan": "9f0a9e780f02c02d025a190f1885e1d1d73b87bd",
"versionType": "git"
},
{
"status": "affected",
"version": "9b54e248d2644be71cb394eb85f31ad99e023a05",
"lessThan": "6644565527c4c5f507088b1c9ddf72de47790b68",
"versionType": "git"
},
{
"status": "affected",
"version": "9b54e248d2644be71cb394eb85f31ad99e023a05",
"lessThan": "5867d7e202e09f037cefe77f7af4413c7c0fa088",
"versionType": "git"
}
],
"programFiles": [
"arch/x86/kvm/svm/sev.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "6.11"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "6.11",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "6.12.93",
"versionType": "semver",
"lessThanOrEqual": "6.12.*"
},
{
"status": "unaffected",
"version": "6.18.35",
"versionType": "semver",
"lessThanOrEqual": "6.18.*"
},
{
"status": "unaffected",
"version": "7.0.12",
"versionType": "semver",
"lessThanOrEqual": "7.0.*"
},
{
"status": "unaffected",
"version": "7.1",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"arch/x86/kvm/svm/sev.c"
],
"defaultStatus": "affected"
}
]- Related CVEs
- CVE-2026-63939
Source reference:
/cveMetadata/cveId
Publisher severity
critical
Source reference: /containers/cna/metrics
- Event
- #40903 · Revision 1
- Added to Heist Feed
- Publisher date