SB20260720311 - Improper access control in Linux kernel ipv6

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Main Vulnerability Database SB20260720311

SB20260720311 - Improper access control in Linux kernel ipv6

Published: July 20, 2026

Security Bulletin ID SB20260720311
CSH Severity
Low
Patch available
YES
Number of vulnerabilities 1
Exploitation vector Local access
Highest impact Data manipulation

Breakdown by Severity

Low 100%
  • Low
  • Medium
  • High
  • Critical

Description

This security bulletin contains information about 1 vulnerability.


1) Improper access control (CVE-ID: CVE-2026-63921)

CWE-ID: CWE-284 - Improper Access Control

CVSSv4: 6.8 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N]


The vulnerability allows a local user to redirect packets across network namespaces.

The vulnerability exists due to improper access control in vti6_siocdevprivate() in the IPv6 VTI tunnel handling code when processing SIOCCHGTUNNEL requests on a migrated tunnel. A local user can supply tunnel parameters that collide with a tunnel in the creation namespace to redirect packets across network namespaces.

Exploitation is reachable from an unprivileged user namespace and can have cross-tenant scope on container hosts.


Remediation

Install update from vendor's website.

References