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CVE Vulnerability Details :
CVE-2026-42493
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 | 12:31
Updated At-28 Jul, 2026 | 16:33
Rejected At-
▼CVE Numbering Authority (CNA)
x86 shadow paging is deprecated

Addressing certain issues, in particular related to operations which may take excessively long and therefore would need preemption, has turned out overly costly. Since alternatives (HVM/PVH: HAP, PV: shim) are commonly available, the decision was to deprecate the functionality, while still retaining it for people to use at their own (security) risk. Memory-wise small enough guests may still be okay to run.

Affected Products
Vendor
Xen ProjectXen
Product
Xen
Default Status
unknown
Versions

unknown

  • consult Xen advisory XSA-495
Metrics
VersionBase scoreBase severityVector
Metrics Other Info
Impacts
CAPEC IDDescription
N/AAn unprivileged guest may be able to cause Denial of Service (DoS) affecting the entire host.
CAPEC ID: N/A
Description: An unprivileged guest may be able to cause Denial of Service (DoS) affecting the entire host.
Solutions
Configurations

All x86 systems with builds of Xen having SHADOW_PAGING=y are affected. Note that prior to Xen 4.7 this control didn't exist, and all builds of Xen would be affected. (Strictly speaking Xen 4.6 had a different, harder to use mechanism to disable shadow paging support: One could pass "shadow-paging=n" on the make command line.)

Workarounds

Running HVM and PVH in Hardware Assisted Paging (HAP) mode will avoid this vulnerability. There's no mitigation available for PV guests. This is because shadow mode, if support is enabled in the hypervisor, could be engaged at any time. Note that without shadow mode built into Xen, guests not properly dealing with L1TF will simply be crashed instead.

Exploits
Credits
Timeline
EventDate
Replaced By
Rejected Reason
References
HyperlinkResource
https://xenbits.xenproject.org/xsa/advisory-495.html
N/A
Hyperlink: https://xenbits.xenproject.org/xsa/advisory-495.html
Resource: N/A
▼Authorized Data Publishers (ADP)
1. CVE Program Container
Affected Products
Metrics
VersionBase scoreBase severityVector
Metrics Other Info
Impacts
CAPEC IDDescription
Solutions
Configurations
Workarounds
Exploits
Credits
Timeline
EventDate
Replaced By
Rejected Reason
References
HyperlinkResource
http://xenbits.xen.org/xsa/advisory-495.html
N/A
http://www.openwall.com/lists/oss-security/2026/07/28/12
N/A
Hyperlink: http://xenbits.xen.org/xsa/advisory-495.html
Resource: N/A
Hyperlink: http://www.openwall.com/lists/oss-security/2026/07/28/12
Resource: N/A
2. CISA ADP Vulnrichment
Affected Products
Problem Types
TypeCWE IDDescription
CWECWE-400CWE-400 Uncontrolled Resource Consumption
Type: CWE
CWE ID: CWE-400
Description: CWE-400 Uncontrolled Resource Consumption
Metrics
VersionBase scoreBase severityVector
3.17.5HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Version: 3.1
Base score: 7.5
Base severity: HIGH
Vector:
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Metrics Other Info
Impacts
CAPEC IDDescription
Solutions
Configurations
Workarounds
Exploits
Credits
Timeline
EventDate
Replaced By
Rejected Reason
References
HyperlinkResource
Details not found