CVE-2026-46120
Description
A flaw was found in the Linux kernel's ip6_gre module. An unprivileged user could exploit this vulnerability by migrating a network device, causing the ip6erspan_changelink() function to incorrectly handle network namespace references. This error leads to a use-after-free condition when the original network namespace is destroyed, potentially resulting in a kernel bug and system instability or denial of service.
Statement
ip6erspan_changelink used dev_net(dev) instead of the cached tunnel net namespace, so after IFLA_NET_NS_FD migration the tunnel could be reinserted into the wrong per netns ip6gre hash while a stale entry remained in the original namespace. Destroying that namespace later can walk the stale entry and trigger a slab use-after-free followed by a kernel BUG in unregister_netdevice_many_notify. For the CVSS the PR:L is used for the paranoid score because the commit states this is reachable from an unprivileged user namespace using unshare with user and net namespaces, not only from full host root. The issue is not directly network reachable by packet traffic and is triggered through local netlink namespace and tunnel lifecycle operations.
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 | 7.1 | N/A | 7.8 |
| Attack Vector | Local | N/A | Local |
| Attack Complexity | Low | N/A | Low |
| Privileges Required | Low | N/A | Low |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | High | N/A | High |
| Integrity Impact | None | N/A | High |
| Availability Impact | High | N/A | High |
Vector
Red Hat: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H
cve.org: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Understanding the Weakness (CWE)
Integrity,Availability,Confidentiality
Technical Impact: Modify Memory; DoS: Crash, Exit, or Restart; Execute Unauthorized Code or Commands
This weakness may result in the corruption of memory, and perhaps instructions, possibly leading to a crash. If the corrupted memory can be effectively controlled, it may be possible to execute arbitrary code.
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