CVE-2026-31788
Description
A flaw was found in the Linux kernel's Xen privcmd driver. This vulnerability allows a root user process within an unprivileged guest (domU) to issue arbitrary hypercalls. Such an action could enable the process to modify the kernel's memory, thereby undermining the secure boot feature designed to protect system integrity.
Statement
A security issue in the Xen privcmd driver allows a root process inside a guest domain to issue unrestricted hypercalls, which can modify kernel memory and bypass secure boot guarantees. This breaks the intended isolation and trust model by allowing a privileged guest user to affect kernel integrity. For the CVSS the PR:H is used for the base score because exploitation requires root access inside the guest domain. The issue is local to Xen environments.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 6.7 | 8.2 | 8.2 |
| Attack Vector | Local | Local | Local |
| Attack Complexity | Low | Low | Low |
| Privileges Required | High | High | High |
| User Interaction | None | None | None |
| Scope | Unchanged | Changed | Changed |
| Confidentiality | High | High | High |
| Integrity Impact | High | High | High |
| Availability Impact | High | High | High |
Vector
Red Hat: CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
NVD: CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H
cve.org: CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H
Understanding the Weakness (CWE)
Access Control
Technical Impact: Gain Privileges or Assume Identity
A user can access restricted functionality and/or sensitive information that may include administrative functionality and user accounts.
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