CVE-2026-62436 Details
Description
[This CNA information record relates to multiple CVEs; the text explains which aspects/vulnerabilities correspond to which CVE.] With the introduction of Grant Table v2 came the requirement to be able to switch between versions. Switching from v1 to v2 reduces the number of valid grant references, as a bigger shared entry structure is then needed while the shared table doesn't change size. Switching from v2 back to v1 the status frames, which are separate in v2, go away. Code holding, but intermediately dropping and then re-acquiring the grant table lock, sometimes wrongly assumes that said properties wouldn't change across the window in time where the lock is not being held. The v1 -> v2 issue is CVE-2026-62435. The v2 -> v1 issue is CVE-2026-62436.
A vulnerability exists in Xen hypervisor versions 4.0 and later, specifically in x86 guests using grant table version 2 interfaces. This vulnerability arises from a race condition during the switching of grant table versions, which can lead to improper handling of grant references. As a result, an unprivileged guest may exploit this issue to elevate privileges to that of the host, potentially causing information leaks and denial-of-service conditions.
To address this vulnerability, apply the appropriate patch available for the specific Xen version in use. For Xen versions 4.13 and newer, grant table support can be disabled, eliminating the vulnerability. Additionally, the 'gnttab=max-ver:1' hypervisor command line option or the 'max_grant_version=1' guest configuration option can be used to avoid the vulnerability.
Metrics
CVSS 4.0 Severity and Vector Strings:
VolerionCVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
Volerion
Assessed Jul 28, 2026CISA-ADP
Assessed Jul 28, 2026References to Advisories, Solutions, and Tools
By selecting these links, you will be leaving this site. These are references gathered from the official CVE record and are not endorsed by Volerion.
| URL | Source(s) | Tag(s) |
|---|---|---|
| https://xenbits.xenproject.org/xsa/advisory-501.html | [email protected] | AdvisoryBundleRemedyVendor |
Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-362 | Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition') | CISA-ADP |
Affected Products
| Product | Versions |
|---|---|
| Xen | >= 4.0, < 4.13 |
CPE
Remediation
| |
Change History
2 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Jul 28, 2026 | CVE Modified | CISA-ADP |
| Jul 28, 2026 | New CVE Received | [email protected] |