---
id: CVE-2026-96276
title: >-
  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 …
summary: >-
  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 …
severity: critical
cvss: 9.8
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H'
cwe:
  - CWE-22
vendor: Red Hat
product: flatpak
affected:
  - flatpak
  - flatpak
  - flatpak
  - flatpak
published: '2026-09-23'
updated: '2026-09-23'
sourceUpdated: '2026-09-23T19:40:10.000'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-96276'
references:
  - url: 'https://access.redhat.com/security/cve/CVE-2026-96276'
    label: secalert@redhat.com
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2539418'
    label: secalert@redhat.com
  - url: 'https://github.com/flatpak/flatpak/security/advisories/GHSA-8qxj-x646-phcm'
    label: secalert@redhat.com
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-96276.json
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-96276'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-96276'
tags:
  - nvd
  - cve.org
  - csaf
  - vex
  - red-hat
ssvc:
  exploitation: none
  automatable: 'yes'
  technicalImpact: total
  timestamp: '2026-09-23T15:28:10.393280Z'
ingestedAt: '2026-09-23T15:26:23.424Z'
epss: 0.00462
epssPercentile: 0.37341
---

## Overview

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.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

## Vendor advisories

- **Red Hat VEX** · Moderate · affected: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 7, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9 · updated 2026-09-23 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-96276.json)