# CVE-2026-63958: usb: typec: ucsi: validate connector number in ucsi_connector_change()

> A malicious USB controller can trigger out-of-bounds memory access in the Linux kernel UCSI driver, potentially causing crashes or code execution.

- **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:** 19 Jul 2026
- **Updated:** 20 Jul 2026
- **Also known as:** BELL-CVE-2026-63958, DEBIAN-CVE-2026-63958, GHSA-qx25-w5h5-ch8m, ROOT-OS-DEBIAN-11-CVE-2026-63958, ROOT-OS-UBUNTU-2204-CVE-2026-63958, UBUNTU-CVE-2026-63958

## What is CVE-2026-63958?

CVE-2026-63958 is a memory corruption vulnerability in Linux, published on 19 Jul 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:

usb: typec: ucsi: validate connector number in ucsi_connector_change()

The connector number in a UCSI CCI notification is a 7-bit field
supplied by the PPM.  ucsi_connector_change() uses it to index the
ucsi->connector[] array without checking it against the number of
connectors the PPM reported at init time, so a buggy or malicious PPM
(EC firmware, or an I2C-attached UCSI controller on the ccg / stm32g0 /
glink transports) can drive schedule_work() on memory past the end of
the array.

Reject connector numbers that are zero or exceed cap.num_connectors
before dereferencing the array.

## Which versions are affected by CVE-2026-63958?


## How do I fix CVE-2026-63958?

Apply the vendor's patch.

## Is CVE-2026-63958 being exploited?

There is no known exploitation of CVE-2026-63958 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-63958 and fix it if it is affected.

What it is: CVE-2026-63958 is a memory corruption vulnerability in Linux, published on 19 Jul 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-2026-63958 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-2026-63958/ (Markdown: https://insights.sbomify.com/CVE-2026-63958/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-63958
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-63958
- OSV: https://osv.dev/vulnerability/CVE-2026-63958

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-63958/
Summaries are generated and may contain mistakes; the official description above is the record.