# CVE-2026-96276: Flatpak: flatpak: arbitrary write in host context via flatpak build-init

> A malicious SDK can write arbitrary files to the host system during flatpak build-init, potentially leading to code execution or privilege escalation.

- **Severity:** Medium 6.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 23 Sep 2026
- **Updated:** 27 Sep 2026
- **Also known as:** DEBIAN-CVE-2026-96276, UBUNTU-CVE-2026-96276

## What is CVE-2026-96276?

CVE-2026-96276 is a medium-severity path traversal vulnerability in Red Hat Enterprise Linux 10, published on 23 Sep 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official description

If a malicious SDK container declares an extension point with a crafted `directory` path, and a developer runs `flatpak build-init --writable-sdk --sdk-extension` with that SDK, attacker-chosen files could be written outside the working directory, since the target path is resolved via a function that allows `..` traversal.

Weakness: CWE-22 (Improper Limitation of a Pathname to a Restricted Directory)

## Which versions are affected by CVE-2026-96276?


## How do I fix CVE-2026-96276?

Apply the vendor's patch.

## Is CVE-2026-96276 being exploited?

There is no known exploitation of CVE-2026-96276 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-96276 and fix it if it is affected.

What it is: CVE-2026-96276 is a medium-severity path traversal vulnerability in Red Hat Enterprise Linux 10, published on 23 Sep 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2026-96276 in the wild and no public exploit code.

Affected product: Red Hat Enterprise Linux 10. 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-2026-96276/ (Markdown: https://insights.sbomify.com/CVE-2026-96276/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-96276
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-96276
- OSV: https://osv.dev/vulnerability/CVE-2026-96276

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-96276/
Summaries are generated and may contain mistakes; the official description above is the record.