CVE-2026-63921
Description
A flaw was found in the Linux kernel's IPv6 Virtual Tunnel Interface (VTI) module. When a VTI tunnel device is moved to a different network environment, an unprivileged user in a separate user space can manipulate tunnel parameters. This manipulation could allow the user to intercept or redirect network traffic intended for other parts of the system or other containers, leading to unauthorized information disclosure or denial of service across different tenants on a container host.
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).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 7 | N/A | 8.8 |
| Attack Vector | Local | N/A | Local |
| Attack Complexity | High | N/A | Low |
| Privileges Required | Low | N/A | Low |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Changed |
| Confidentiality | High | N/A | High |
| Integrity Impact | High | N/A | High |
| Availability Impact | High | N/A | High |
Vector
Red Hat: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
cve.org: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
Understanding the Weakness (CWE)
Access Control
Technical Impact: Gain Privileges or Assume Identity; Bypass Protection Mechanism
The exploitation of a weakness in low-privileged areas of the software can be leveraged to reach higher-privileged areas without having to overcome any additional obstacles.
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