CVE-2026-72391
Received Received - Intake

Memory Leak in Linux Kernel SFP Module

Vulnerability report for CVE-2026-72391, including description, CVSS score, EPSS score, affected products, exploitability, helpful resources, and attack-flow context.

Publication date: 2026-08-15

Last updated on: 2026-08-15

Assigner: kernel.org

Description

In the Linux kernel, the following vulnerability has been resolved: net: phy: sfp: free mii_bus in sfp_i2c_mdiobus_destroy sfp_i2c_mdiobus_create() allocates the I2C MDIO bus with mdio_i2c_alloc(), a plain (non-devm) allocation, and registers it. sfp_i2c_mdiobus_destroy() only unregisters the bus and clears sfp->i2c_mii without calling mdiobus_free(). As the only reference to the bus is then cleared, the struct mii_bus is leaked. This is hit whenever a copper/RollBall SFP module that instantiated an MDIO bus is removed: sfp_sm_main() takes the global teardown path and calls sfp_i2c_mdiobus_destroy(). sfp_cleanup(), on driver unbind, frees sfp->i2c_mii directly, which is why the leak only triggered on module hot-removal and not on unbind. Free the bus in sfp_i2c_mdiobus_destroy() to match the allocation done in sfp_i2c_mdiobus_create().

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Meta Information

Published
2026-08-15
Last Modified
2026-08-15
Generated
2026-08-15
AI Q&A
2026-08-15
EPSS Evaluated
N/A
NVD
EUVD

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
linux linux_kernel *

Helpful Resources

Exploitability

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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This vulnerability is a memory leak in the Linux kernel's SFP (Small Form-factor Pluggable) module handling. When a copper or RollBall SFP module is removed, the kernel fails to properly free the I2C MDIO bus memory allocated during module initialization. The bus is allocated but never freed, causing a resource leak.

Detection Guidance

This vulnerability is specific to Linux kernel's SFP module handling and may not have direct network detection commands. Check kernel logs for SFP module removal events or memory leaks using dmesg | grep sfp or journalctl -k | grep sfp. Monitor mii_bus allocations with slabtop or cat /proc/slabinfo.

Impact Analysis

The impact is primarily on system stability and resource usage. Over time, repeated SFP module insertions and removals could exhaust available memory, leading to performance degradation or system crashes. It affects systems using SFP modules with MDIO bus functionality.

Mitigation Strategies

Update the Linux kernel to a patched version where sfp_i2c_mdiobus_destroy() properly frees the mii_bus. Avoid hot-removing copper/RollBall SFP modules until patched. Monitor system memory usage for leaks after SFP module removal.

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