CVE-2025-38110
Description
A flaw was found in the Linux kernel's MDIO (Management Data Input/Output) bus subsystem. This vulnerability allows a local user with administrative privileges to cause memory corruption or information disclosure by supplying an out-of-range physical layer (PHY) address through an input/output control (ioctl) command. Due to missing boundary checks during Clause 45 operations, the kernel accesses an internal statistics array beyond its allocated bounds.
Statement
A bounds check was missing in the __mdiobus_c45_read() and __mdiobus_c45_write() functions, allowing out-of-bounds access to the stats array in the kernel if a user supplied an invalid PHY address via an ioctl. Although the read/write would typically fail on hardware, the statistics array was still accessed, potentially leading to an out-of-bounds memory read/write in kernel space. This patch adds a check that ensures the PHY address does not exceed PHY_MAX_ADDR, mitigating the risk. The Privileges required for the CVSS is High (PR: H), because requires administrative privileges to issue raw ioctl commands to a network interface (typically CAP_NET_ADMIN). Potential memory corruption could happen inside the firmware of the networking hardware, but not for the memory of the Linux Kernel, and this is the reason why no Kernel Crash could be (and A:N for CVSS).
Mitigation
To mitigate this issue, prevent module mdio from being loaded. Please see https://access.redhat.com/solutions/41278 for how to blacklist a kernel module to prevent it from loading automatically.
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 | 6 | 7.1 | 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 | High | High | High |
| Integrity Impact | High | None | High |
| Availability Impact | None | High | High |
Vector
Red Hat: CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:N
NVD: 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)
Other,Integrity,Availability
Technical Impact: Varies by Context; DoS: Resource Consumption (CPU); Modify Memory; Read Memory
When the quantity is not properly validated, then attackers can specify malicious quantities to cause excessive resource allocation, trigger unexpected failures, enable buffer overflows, etc.
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