# CVE-2026-98025: net: usb: cx82310_eth: drop URB after 0xffff reboot sentinel to prevent partial_data heap overflow

> A heap overflow in the Linux kernel cx82310_eth USB driver allows attackers with physical USB access to execute code or crash the system via crafted packets.

- **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:** 25 Sep 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-104468, BELL-CVE-2026-98025, DEBIAN-CVE-2026-98025, GHSA-wcwv-8f76-pq3h, UBUNTU-CVE-2026-98025

## What is CVE-2026-98025?

CVE-2026-98025 is a memory corruption vulnerability in Linux, published on 25 Sep 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: usb: cx82310_eth: drop URB after 0xffff reboot sentinel to prevent partial_data heap overflow

The 0xffff length sentinel detects a router reboot and schedules
re-enabling of ethernet mode, but then falls through to the rest
of the loop body.  The next check is

	} else if (len > CX82310_MTU) {

which is the else of the just-matched if -- it never fires for
len == 0xffff.  The MTU bound that normally caps the
incomplete-packet save path is silently bypassed.

With 0xffff > skb->len always true (rx_urb_size is 4096), the
incomplete-packet branch saves dev->partial_len = skb->len bytes
into dev->partial_data.  partial_data is kmalloc(hard_mtu) =
kmalloc(CX82310_MTU + 2) = 1516 bytes, but skb->len after the
2-byte header pull can be up to 4094.  A device that sends a
4096-byte URB starting with [0xff 0xff] therefore copies 4094
device-provided bytes into a buffer allocated for 1516 bytes,
exceeding its requested size by 2578 bytes.

The next URB then reads dev->partial_len (4094) back from the same
1516-byte buffer and dev->partial_rem (65535 - 4094 = 61441) from
the new URB's ~4KB skb, both well past their allocations, and
delivers the spliced result as a 64KB "frame" to the network
stack.

Bail out of rx_fixup after scheduling the re-enable work; the
remainder of a reboot-marker URB is not meaningful packet data.
This restores the invariant that partial_len < CX82310_MTU + 2 on
the save path, since every other route there has already passed
the MTU check.

## Which versions are affected by CVE-2026-98025?


## How do I fix CVE-2026-98025?

Apply the vendor's patch.

## Is CVE-2026-98025 being exploited?

There is no known exploitation of CVE-2026-98025 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-98025 and fix it if it is affected.

What it is: CVE-2026-98025 is a memory corruption vulnerability in Linux, published on 25 Sep 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-2026-98025 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-2026-98025/ (Markdown: https://insights.sbomify.com/CVE-2026-98025/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-98025
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-98025
- OSV: https://osv.dev/vulnerability/CVE-2026-98025

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-98025/
Summaries are generated and may contain mistakes; the official description above is the record.