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CVE-2025-40251 high CVSS 7.8

Vulnerability in Linux kernel (CVE-2025-40251)

Summary

Vulnerability in Linux kernel (CVE-2025-40251). Successful exploitation can lead to full system takeover. Exploitable via rate_leaf_parent_set.

Original description

The description as published by the source.

In the Linux kernel, the following vulnerability has been resolved:

devlink: rate: Unset parent pointer in devl_rate_nodes_destroy

The function devl_rate_nodes_destroy is documented to "Unset parent for
all rate objects". However, it was only calling the driver-specific
rate_leaf_parent_set or rate_node_parent_set ops and decrementing
the parent's refcount, without actually setting the
devlink_rate->parent pointer to NULL.

This leaves a dangling pointer in the devlink_rate struct, which cause
refcount error in netdevsim[1] and mlx5[2]. In addition, this is
inconsistent with the behavior of devlink_nl_rate_parent_node_set,
where the parent pointer is correctly cleared.

This patch fixes the issue by explicitly setting devlink_rate->parent
to NULL after notifying the driver, thus fulfilling the function's
documented behavior for all rate objects.

[1]
repro steps:
echo 1 > /sys/bus/netdevsim/new_device
devlink dev eswitch set netdevsim/netdevsim1 mode switchdev
echo 1 > /sys/bus/netdevsim/devices/netdevsim1/sriov_numvfs
devlink port function rate add netdevsim/netdevsim1/test_node
devlink port function rate set netdevsim/netdevsim1/128 parent test_node
echo 1 > /sys/bus/netdevsim/del_device

dmesg:
refcount_t: decrement hit 0; leaking memory.
WARNING: CPU: 8 PID: 1530 at lib/refcount.c:31 refcount_warn_saturate+0x42/0xe0
CPU: 8 UID: 0 PID: 1530 Comm: bash Not tainted 6.18.0-rc4+ #1 NONE
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.16.0-0-gd23955…

Source: NIST National Vulnerability Database NVD GitHub Advisory

Auto-generated summary

Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.

A vulnerability tracked as CVE-2025-40251 has been found in Linux kernel.
Attackers can target a specific entry point like rate_leaf_parent_set over the network to misuse the product.
Successful exploitation can lead to full system takeover. CVSS score: 7.8/10.
What to do: apply the vendor's official patched release.
If unsure, ask your IT team or search "Linux kernel CVE-2025-40251" on the vendor's site.

CVE-2025-40251 (Linux kernel) — CWE-476 / CVSS v3 7.8
Attack vector: local / no user interaction
Attack surface: rate_leaf_parent_set / rate_node_parent_set / devlink_rate / devlink_nl_rate_parent_node_set
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.

❓ What is the problem

A vulnerability (CWE-476) exists in Linux kernel. Attackers reach the vulnerable code path via rate_leaf_parent_set.

📍 Affected scope

Check the vendor advisory for the affected versions of Linux kernel. Attack surface: rate_leaf_parent_set / rate_node_parent_set / devlink_rate / devlink_nl_rate_parent_node_set.

🔥 Severity

Severity: High (CVSS 7.8/10). Successful exploitation can lead to full system takeover.

🔧 How to fix

Update to the patched release per vendor advisory.

🛡️ Workaround

Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.

🔍 Detection

Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Audit SBOM/dependencies to find affected services.

Response actions

Concrete steps and command examples for SOC/SRE teams to execute in order

  1. 1
    Identify exposure identify 
    Audit SBOM/dependencies for affected components.

    資産台帳・SBOM・依存マニフェストで Linux kernel を使っているサービスとバージョンを洗い出す。

  2. 2
    Post-deployment verification verify 
    Confirm patched version is live in production

    パッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。

Affected packages

Linux Kernel
[{"type":"ECOSYSTEM","events":[{"introduced":"5.14.0"},{"fixed":"6.1.164"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.2.0"},{"fixed":"6.6.118"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.60"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.17.10"}]}]

Fix status by distribution

Fixed packages published by each distribution for this CVE

References

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