CVE-2025-38678
Description
From CVE.org
In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_tables: reject duplicate device on updates A chain/flowtable update with duplicated devices in the same batch is possible. Unfortunately, netdev event path only removes the first device that is found, leaving unregistered the hook of the duplicated device. Check if a duplicated device exists in the transaction batch, bail out with EEXIST in such case. WARNING is hit when unregistering the hook: [49042.221275] WARNING: CPU: 4 PID: 8425 at net/netfilter/core.c:340 nf_hook_entry_head+0xaa/0x150 [49042.221375] CPU: 4 UID: 0 PID: 8425 Comm: nft Tainted: G S 6.16.0+ #170 PREEMPT(full) [...] [49042.221382] RIP: 0010:nf_hook_entry_head+0xaa/0x150
Statement
A flaw in nf_tables allowed a chain/flowtable update batch to include the same netdevice more than once. This left the hook lists in an inconsistent state (one duplicate not properly unregistered), triggering kernel WARNs and risking a later crash during hook teardown. Exploitation requires local CAP_NET_ADMIN (e.g., via nft in the host or a privileged netns). High privileges are required because only processes with administrative capabilities (e.g., CAP_NET_ADMIN) can create or update nftables chains or flowtables, so unprivileged users cannot directly trigger this condition.
Mitigation
In order to trigger the issue, it requires the ability to create user/net namespaces.
On non-containerized deployments of Red Hat Enterprise Linux 8, you can disable user namespaces by setting user.max_user_namespaces to 0:
# echo "user.max_user_namespaces=0" > /etc/sysctl.d/userns.conf
# sysctl -p /etc/sysctl.d/userns.conf
On containerized deployments, such as Red Hat OpenShift Container Platform, do not use this mitigation as the functionality is needed to be enabled.
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 | 4.4 | 5.5 | 7.8 |
| Attack Vector | Local | Local | Local |
| Attack Complexity | Low | Low | Low |
| Privileges Required | High | Low | Low |
| User Interaction | None | None | None |
| Scope | Unchanged | Unchanged | Unchanged |
| Confidentiality | None | None | High |
| Integrity Impact | None | None | High |
| Availability Impact | High | High | High |
Vector
Red Hat: CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H
NVD: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/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)
Availability
Technical Impact: DoS: Crash, Exit, or Restart; DoS: Resource Consumption (CPU); DoS: Resource Consumption (Memory)
An attacker could provide unexpected values and cause a program crash or arbitrary control of resource allocation, leading to excessive consumption of resources such as memory and CPU.
Confidentiality
Technical Impact: Read Memory; Read Files or Directories
An attacker could read confidential data if they are able to control resource references.
Integrity,Confidentiality,Availability
Technical Impact: Modify Memory; Execute Unauthorized Code or Commands
An attacker could use malicious input to modify data or possibly alter control flow in unexpected ways, including arbitrary command execution.
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