SB2026012786 - Citrix XenServer update for Xen

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Main Vulnerability Database SB2026012786

SB2026012786 - Citrix XenServer update for Xen

Published: January 27, 2026

Security Bulletin ID SB2026012786
CSH Severity
Low
Patch available
YES
Number of vulnerabilities 2
Exploitation vector Local access
Highest impact Code execution

Breakdown by Severity

Low 100%
  • Low
  • Medium
  • High
  • Critical

Description

This security bulletin contains information about 2 vulnerabilities.


1) Time-of-check Time-of-use (TOCTOU) Race Condition (CVE-ID: CVE-2025-58151)

CWE-ID: CWE-367 - Time-of-check Time-of-use (TOCTOU) Race Condition

CVSSv4: CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:N/SC:H/SI:H/SA:H/E:U/U:Clear


The vulnerability allows a local user to escalate privileges on the system.

The vulnerability exists due to a race condition in varstored. A local user with kernel level access in a VM can escalate privilege via gaining code execution within varstored.


2) Permissions, Privileges, and Access Controls (CVE-ID: CVE-2026-23553)

CWE-ID: CWE-264 - Permissions, Privileges, and Access Controls

CVSSv4: CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:U/U:Clear


The vulnerability allows a local user to gain access to sensitive information.

The vulnerability exists due to incomplete IBPB for vCPU isolation. A guest processes can leverage information leaks to obtain information intended to be private to other entities in a guest.


Remediation

Install update from vendor's website.

References