# CVE-2026-74678: net: usb: ax88179_178a: fix skb leak in ax88179_tx_fixup()

> A memory leak in the Linux kernel's ax88179_178a USB network driver can cause resource exhaustion and denial of service under memory pressure.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 22 Aug 2026
- **Updated:** 16 Oct 2026
- **Also known as:** AZL-97359, BELL-CVE-2026-74678, DEBIAN-CVE-2026-74678, GHSA-5prv-rfcq-7r84, UBUNTU-CVE-2026-74678

## What is CVE-2026-74678?

CVE-2026-74678 is a high-severity denial of service vulnerability in Linux, published on 22 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

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

net: usb: ax88179_178a: fix skb leak in ax88179_tx_fixup()

When the interface has NETIF_F_SG enabled and skb_linearize() fails in
ax88179_tx_fixup(), the function returns NULL without freeing the skb.

usbnet_start_xmit() treats a NULL return from tx_fixup() as a drop
(info->flags does not set FLAG_MULTI_PACKET for this driver), jumping
to the "drop" label where it does `if (skb) dev_kfree_skb_any(skb)`.
Because tx_fixup() returned NULL, the local skb variable in
usbnet_start_xmit() is NULL, so the original skb is never freed — a
memory leak on every TX frame whose linearization fails (i.e. under
memory pressure).

Free the skb before returning, matching the error handling already used
for the pskb_expand_head() failure path in the same function.

## Which versions are affected by CVE-2026-74678?


## How do I fix CVE-2026-74678?

Apply the vendor's patch.

## Is CVE-2026-74678 being exploited?

There is no known exploitation of CVE-2026-74678 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-74678 and fix it if it is affected.

What it is: CVE-2026-74678 is a high-severity denial of service vulnerability in Linux, published on 22 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-74678 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-2026-74678/ (Markdown: https://insights.sbomify.com/CVE-2026-74678/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-74678
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-74678
- OSV: https://osv.dev/vulnerability/CVE-2026-74678

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-74678/
Summaries are generated and may contain mistakes; the official description above is the record.