Answer in brief
CVE-2026-63939 records a Unknown severity vulnerability in KVM: SEV: Compute the correct max length of the in-GHCB scratch area. The current sources do not mark it as known exploited. The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
A CVSS score is not reported in the current record. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| Linux/Linuxgeneric | >=9b54e248d2644be71cb394eb85f31ad99e023a05 <6ca9400d36005ffdca25f80186bea781c7e1dc4c || >=9b54e248d2644be71cb394eb85f31ad99e023a05 <9f0a9e780f02c02d025a190f1885e1d1d73b87bd || >=9b54e248d2644be71cb394eb85f31ad99e023a05 <6644565527c4c5f507088b1c9ddf72de47790b68 || >=9b54e248d2644be71cb394eb85f31ad99e023a05 <5867d7e202e09f037cefe77f7af4413c7c0fa088 | 6ca9400d36005ffdca25f80186bea781c7e1dc4c, 9f0a9e780f02c02d025a190f1885e1d1d73b87bd, 6644565527c4c5f507088b1c9ddf72de47790b68, 5867d7e202e09f037cefe77f7af4413c7c0fa088 |
| Linux/Linuxgeneric | 6.11 | Not reported |
Published upstream
Jul 19, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Aug 5, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Aug 5, 2026
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.
Quoted source text, attributed separately from HOL analysis.
Answer in brief
CVE-2026-63939 records a Unknown severity vulnerability in KVM: SEV: Compute the correct max length of the in-GHCB scratch area. The current sources do not mark it as known exploited. The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
A CVSS score is not reported in the current record. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| Linux/Linuxgeneric | >=9b54e248d2644be71cb394eb85f31ad99e023a05 <6ca9400d36005ffdca25f80186bea781c7e1dc4c || >=9b54e248d2644be71cb394eb85f31ad99e023a05 <9f0a9e780f02c02d025a190f1885e1d1d73b87bd || >=9b54e248d2644be71cb394eb85f31ad99e023a05 <6644565527c4c5f507088b1c9ddf72de47790b68 || >=9b54e248d2644be71cb394eb85f31ad99e023a05 <5867d7e202e09f037cefe77f7af4413c7c0fa088 | 6ca9400d36005ffdca25f80186bea781c7e1dc4c, 9f0a9e780f02c02d025a190f1885e1d1d73b87bd, 6644565527c4c5f507088b1c9ddf72de47790b68, 5867d7e202e09f037cefe77f7af4413c7c0fa088 |
| Linux/Linuxgeneric | 6.11 | Not reported |
Published upstream
Jul 19, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Aug 5, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Aug 5, 2026
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.
Quoted source text, attributed separately from HOL analysis.