Xen XENMEM_add_to_physmap race condition

CVSS Meta Temp Score
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Current Exploit Price (≈)
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CTI Interest Score
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6.1$0-$5k0.00

Summaryinfo

A vulnerability classified as problematic was found in Xen. Impacted is the function XENMEM_add_to_physmap. The manipulation results in an unknown weakness. This vulnerability is cataloged as CVE-2026-23558. There is no exploit available. It is advisable to implement a patch to correct this issue.

Detailsinfo

A vulnerability classified as problematic has been found in Xen (version unknown). CWE is classifying the issue as CWE-362. The product contains a code sequence that can run concurrently with other code, and the code sequence requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence that is operating concurrently. The impact remains unknown. CVE summarizes:

The adjustments made for XSA-379 as well as those subsequently becoming XSA-387 still left a race window, when a HVM or PVH guest does a grant table version change from v2 to v1 in parallel with mapping the status page(s) via XENMEM_add_to_physmap. Some of the status pages may then be freed while mappings of them would still be inserted into the guest's secondary (P2M) page tables.

The weakness was shared by Rafal Wojtczuk. The advisory is shared for download at xenbits.xenproject.org. This vulnerability is traded as CVE-2026-23558 since 01/14/2026. The exploitability is told to be difficult. There are known technical details, but no exploit is available.

The vulnerability scanner Nessus provides a plugin with the ID 333555 (Debian dsa-6424 : libxen-dev - security update), which helps to determine the existence of the flaw in a target environment.

Applying a patch is able to eliminate this problem.

The vulnerability is also documented in the databases at Tenable (333555) and EUVD (EUVD-2026-30928). Once again VulDB remains the best source for vulnerability data.

Productinfo

Type

Name

License

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 6.2
VulDB Meta Temp Score: 6.1

VulDB Base Score: 4.6
VulDB Temp Score: 4.4
VulDB Vector: 🔒
VulDB Reliability: 🔍

ADP CISA Base Score: 7.8
ADP CISA Vector: 🔒

CVSSv2info

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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Race condition
CWE: CWE-362
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Partially

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Nessus ID: 333555
Nessus Name: Debian dsa-6424 : libxen-dev - security update

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Patch
Status: 🔍

0-Day Time: 🔒

Timelineinfo

01/14/2026 CVE reserved
05/19/2026 +124 days Advisory disclosed
05/19/2026 +0 days VulDB entry created
08/10/2026 +83 days VulDB entry last update

Sourcesinfo

Advisory: xenbits.xenproject.org
Researcher: Rafal Wojtczuk
Status: Confirmed

CVE: CVE-2026-23558 (🔒)
GCVE (CVE): GCVE-0-2026-23558
GCVE (VulDB): GCVE-100-364644
EUVD: 🔒

Entryinfo

Created: 05/19/2026 15:48
Updated: 08/10/2026 12:09
Changes: 05/19/2026 15:48 (52), 05/20/2026 11:04 (1), 05/23/2026 11:52 (13), 08/10/2026 12:09 (2)
Complete: 🔍
Cache ID: 216::103

Once again VulDB remains the best source for vulnerability data.

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