CVE-2026-63940
KVM: SEV: Ignore Port I/O requests of length '0'
Description
In the Linux kernel, the following vulnerability has been resolved: KVM: SEV: Ignore Port I/O requests of length '0' Explicitly ignore Port I/O requests of length '0' (or count '0'), so that setting up the software scratch area (and other code) doesn't have to worry about underflowing the length, and to allow for WARNing on trying to configure the scratch area with len==0.
INFO
Published Date :
July 19, 2026, 4:17 p.m.
Last Modified :
July 27, 2026, 5:44 p.m.
Remotely Exploit :
No
Source :
416baaa9-dc9f-4396-8d5f-8c081fb06d67
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 3.1 | CRITICAL | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 |
Solution
- Apply the latest Linux kernel security patches.
- Update the Linux kernel to the resolved version.
- Verify the kernel version after applying updates.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-63940.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-63940 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-63940
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-63940 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-63940 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
CVE Modified by 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Jul. 20, 2026
Action Type Old Value New Value Added CVSS V3.1 AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H -
New CVE Received by 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Jul. 19, 2026
Action Type Old Value New Value Added Affected [{'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '291bd20d5d88814a73d43b55b9428feab2f28094', 'lessThan': '3b6035bc6bff20e89752ce4358bc4c9a9d5883f2', 'versionType': 'git'}, {'status': 'affected', 'version': '291bd20d5d88814a73d43b55b9428feab2f28094', 'lessThan': '2254972d4d69e279ba4e87bf0968eb08ad0d3c92', 'versionType': 'git'}, {'status': 'affected', 'version': '291bd20d5d88814a73d43b55b9428feab2f28094', 'lessThan': 'c30cde934c7813b4e3069765dac64ce3d31e34f2', 'versionType': 'git'}, {'status': 'affected', 'version': '291bd20d5d88814a73d43b55b9428feab2f28094', 'lessThan': '3988bd2723de407ae90fa7a6f6029b4e60238c58', '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': '5.11'}, {'status': 'unaffected', 'version': '0', 'lessThan': '5.11', 'versionType': 'semver'}, {'status': 'unaffected', 'version': '6.12.95', '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'}] Added Description In the Linux kernel, the following vulnerability has been resolved: KVM: SEV: Ignore Port I/O requests of length '0' Explicitly ignore Port I/O requests of length '0' (or count '0'), so that setting up the software scratch area (and other code) doesn't have to worry about underflowing the length, and to allow for WARNing on trying to configure the scratch area with len==0. Added Reference https://git.kernel.org/stable/c/2254972d4d69e279ba4e87bf0968eb08ad0d3c92 Added Reference https://git.kernel.org/stable/c/3988bd2723de407ae90fa7a6f6029b4e60238c58 Added Reference https://git.kernel.org/stable/c/3b6035bc6bff20e89752ce4358bc4c9a9d5883f2 Added Reference https://git.kernel.org/stable/c/c30cde934c7813b4e3069765dac64ce3d31e34f2