CVE-2026-62435 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 race condition vulnerability has been identified in Xen's grant table management, specifically in versions 4.0 and later. This vulnerability arises from the introduction of Grant Table v2, which requires switching between grant table versions. Unprivileged x86 guests with multi-vCPU configurations, allowed to use grant table v2 interfaces, can exploit this vulnerability to improperly assume that certain properties would remain unchanged while the grant table lock is temporarily released. As a result, this could lead to unauthorized privilege escalation to the host level, along with potential 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, which can be built without grant table support, this vulnerability can be avoided by turning off grant table support in the hypervisor configuration. Additionally, for guests, the 'max_grant_version=1' configuration option can be used to prevent 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] |