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CVE Vulnerability Details :
CVE-2026-62435
PUBLISHED
More InfoOfficial Page
Assigner-XEN
Assigner Org ID-23aa2041-22e1-471f-9209-9b7396fa234f
View Known Exploited Vulnerability (KEV) details
Published At-28 Jul, 2026 | 12:32
Updated At-28 Jul, 2026 | 15:19
Rejected At-
▼CVE Numbering Authority (CNA)
grant-table: version change racing with other operations

[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.

Affected Products
Vendor
Xen ProjectXen
Product
Xen
Default Status
unknown
Versions

unknown

  • consult Xen advisory XSA-501
Metrics
VersionBase scoreBase severityVector
Metrics Other Info
Impacts
CAPEC IDDescription
N/AAn unprivileged guest may be able to elevate its privileges to that of the host. Information leaks and Denial of Service (DoS) are possible as well.
CAPEC ID: N/A
Description: An unprivileged guest may be able to elevate its privileges to that of the host. Information leaks and Denial of Service (DoS) are possible as well.
Solutions

Configurations

All Xen versions from 4.0 onwards are vulnerable. Xen versions 3.4 and earlier are not vulnerable. Only x86 guests permitted to use grant table version 2 interfaces can leverage this vulnerability. On Arm, grant table v2 use is explicitly unsupported. Only multi-vCPU guests can leverage this vulnerability. Xen versions 4.13 and newer offer a way to build Xen without grant table support. Such hypervisors (CONFIG_GRANT_TABLE turned off) are not vulnerable.

Workarounds

Using the "gnttab=max-ver:1" hypervisor command line option will avoid the vulnerability. Using the "max_grant_version=1" guest configuration option for guests will also avoid the vulnerability.

Exploits

Credits

finder
This issue was discovered by Mark Esler.
Timeline
EventDate
Replaced By

Rejected Reason

References
HyperlinkResource
https://xenbits.xenproject.org/xsa/advisory-501.html
N/A
Hyperlink: https://xenbits.xenproject.org/xsa/advisory-501.html
Resource: N/A
▼Authorized Data Publishers (ADP)
CISA ADP Vulnrichment
Affected Products
Problem Types
TypeCWE IDDescription
CWECWE-362CWE-362 Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')
Type: CWE
CWE ID: CWE-362
Description: CWE-362 Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')
Metrics
VersionBase scoreBase severityVector
3.16.5MEDIUM
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:L
Version: 3.1
Base score: 6.5
Base severity: MEDIUM
Vector:
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:L
Metrics Other Info
Impacts
CAPEC IDDescription
Solutions

Configurations

Workarounds

Exploits

Credits

Timeline
EventDate
Replaced By

Rejected Reason

References
HyperlinkResource
Details not found