# CVE-2026-42478: Null dereference in n/a

> Attackers can cause denial of service in Open CASCADE Technology via crafted VRML files triggering null pointer dereference.

- **Severity:** Medium 5.5 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 1 May 2026
- **Updated:** 1 May 2026
- **Also known as:** DEBIAN-CVE-2026-42478, GHSA-9mvh-w57g-g5m8, UBUNTU-CVE-2026-42478

## What is CVE-2026-42478?

CVE-2026-42478 is a medium-severity vulnerability in n/a, published on 1 May 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

An issue was discovered in VrmlData_IndexedFaceSet::TShape in the VRML V2.0 parser in Open CASCADE Technology (OCCT) V8_0_0_rc5 allows attackers to cause a denial of service via a crafted VRML file. The issue occurs because malformed VRML input can trigger dereference of a corrupt or unvalidated pointer during shape construction in libTKDEVRML.so.

Weakness: CWE-476 (NULL Pointer Dereference), CWE-125 (Out-of-bounds Read)

## Which versions are affected by CVE-2026-42478?

It affects 1 product.


Products: Opencascade Open Cascade Technology.

## How do I fix CVE-2026-42478?

No fix has been published for CVE-2026-42478 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-42478 being exploited?

There is no known exploitation of CVE-2026-42478 in the wild and no public exploit code.

## Other vulnerabilities in n/a

- [CVE-2026-42476](https://insights.sbomify.com/CVE-2026-42476/): Memory corruption in n/a (medium 5.5)
- [CVE-2026-42477](https://insights.sbomify.com/CVE-2026-42477/): Memory corruption in n/a (medium 5.5)
- [CVE-2026-42479](https://insights.sbomify.com/CVE-2026-42479/): Denial of service in n/a (medium 5.5)
- [CVE-2026-42480](https://insights.sbomify.com/CVE-2026-42480/): Denial of service in n/a (medium 5.5)
- [CVE-2026-42481](https://insights.sbomify.com/CVE-2026-42481/): Memory corruption in n/a (medium 5.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-42478 and fix it if it is affected.

What it is: CVE-2026-42478 is a medium-severity vulnerability in n/a, published on 1 May 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-2026-42478 in the wild and no public exploit code.

Affected product: n/a. 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-2026-42478/ (Markdown: https://insights.sbomify.com/CVE-2026-42478/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-42478
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-42478
- OSV: https://osv.dev/vulnerability/CVE-2026-42478

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-42478/
Summaries are generated and may contain mistakes; the official description above is the record.