# CVE-2026-63857: net: airoha: Do not read uninitialized fragment address in airoha_dev_xmit()

> A Linux kernel driver bug reads uninitialized memory, potentially causing a page fault and system crash.

- **Severity:** Critical 9.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/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:** 19 Jul 2026
- **Updated:** 21 Oct 2026
- **Also known as:** BELL-CVE-2026-63857, DEBIAN-CVE-2026-63857, GHSA-93j7-q4pr-7pmf, ROOT-OS-DEBIAN-13-CVE-2026-63857, UBUNTU-CVE-2026-63857

## What is CVE-2026-63857?

CVE-2026-63857 is a critical vulnerability in Linux, published on 19 Jul 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: airoha: Do not read uninitialized fragment address in airoha_dev_xmit()

The transmit loop in airoha_dev_xmit() reads fragment address and length
during its final iteration, when the loop index equals
skb_shinfo(skb)->nr_frags, at which point the fragment data is
uninitialized. While these values are never consumed, the read itself is
unsafe and may trigger a page fault. Fix this by avoiding the fragment
read on the last iteration.
Additionally, move the skb pointer from the first to the last used packet
descriptor, so that airoha_qdma_tx_napi_poll() defers freeing the skb
until the final descriptor is processed.

## Which versions are affected by CVE-2026-63857?


## How do I fix CVE-2026-63857?

Apply the vendor's patch.

## Is CVE-2026-63857 being exploited?

There is no known exploitation of CVE-2026-63857 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-63857 and fix it if it is affected.

What it is: CVE-2026-63857 is a critical vulnerability in Linux, published on 19 Jul 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-2026-63857 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-2026-63857/ (Markdown: https://insights.sbomify.com/CVE-2026-63857/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-63857
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-63857
- OSV: https://osv.dev/vulnerability/CVE-2026-63857

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-63857/
Summaries are generated and may contain mistakes; the official description above is the record.