grant-table: version change racing with other operations

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-62436
StatePUBLISHED
AssignerXEN
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-07-28 13:19:02 UTC
Updated2026-07-28 16:19:41 UTC
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.

Risk And Classification

Primary CVSS: v3.1 6.5 MEDIUM from ADP

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:L

EPSS: 0.001950000 probability, percentile 0.095680000 (date 2026-07-29)

Problem Types: CWE-362 | CWE-362 CWE-362 Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')

VersionSourceTypeScoreSeverityVector
3.1ADPDECLARED6.5MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:L
3.1134c704f-9b21-4f2e-91b3-4a467353bcc0Secondary6.5MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:L

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
None
Availability
Low

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:L

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Xen Xen unknown consult Xen advisory XSA-501 Not specified

References

ReferenceSourceLinkTags
xenbits.xenproject.org/xsa/advisory-501.html [email protected] xenbits.xenproject.org
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Vendor Comments And Credit

Discovery Credit

CNA: This issue was discovered by Mark Esler. (en)

Additional Advisory Data

Workarounds

CNA: 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.

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