# CVE-2026-72391: net: phy: sfp: free mii_bus in sfp_i2c_mdiobus_destroy

> A memory leak in the Linux kernel SFP driver allows attackers to cause denial of service by repeatedly removing copper SFP modules.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 15 Aug 2026
- **Updated:** 17 Aug 2026
- **Also known as:** BELL-CVE-2026-72391, DEBIAN-CVE-2026-72391, GHSA-j3vv-g378-r9j2, UBUNTU-CVE-2026-72391

## What is CVE-2026-72391?

CVE-2026-72391 is a memory corruption vulnerability in Linux, published on 15 Aug 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official 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().

## Which versions are affected by CVE-2026-72391?


## How do I fix CVE-2026-72391?

Apply the vendor's patch.

## Is CVE-2026-72391 being exploited?

There is no known exploitation of CVE-2026-72391 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-72391 and fix it if it is affected.

What it is: CVE-2026-72391 is a memory corruption vulnerability in Linux, published on 15 Aug 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-72391 in the wild and no public exploit code.

Affected product: Linux. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-72391/ (Markdown: https://insights.sbomify.com/CVE-2026-72391/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-72391
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-72391
- OSV: https://osv.dev/vulnerability/CVE-2026-72391

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-72391/
Summaries are generated and may contain mistakes; the official description above is the record.