CVE-2026-96276
Received Received - Intake

Flatpak SDK Extension Directory Traversal Vulnerability

Publication date: 2026-09-23

Last updated on: 2026-09-23

Assigner: redhat-SADP

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.

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Meta Information

Published
2026-09-23
Last Modified
2026-09-23
Generated
2026-09-23
AI Q&A
2026-09-23
EPSS Evaluated
N/A
NVD
CVE-2026-96276
EUVD
EUVD-2026-85343

Affected Vendors & Products

Showing 3 associated CPEs
Vendor Product Version / Range
flatpak flatpak to 1.18.0 (inc)
flatpak flatpak 1.18.1
flatpak flatpak 1.16.x

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-22 The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory.

Attack-Flow Graph

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Executive Summary

CVE-2026-96276 is a path traversal vulnerability in Flatpak, a Linux application sandboxing framework. It occurs when a malicious SDK container declares an extension point with a crafted directory path containing '..' sequences. When a developer runs 'flatpak build-init --writable-sdk --sdk-extension' with this SDK, attacker-controlled files can be written outside the intended working directory due to improper path resolution using 'g_file_resolve_relative_path'.

Detection Guidance

To detect this vulnerability, check your Flatpak version with 'flatpak --version'. If it is 1.18.0 or earlier, your system is vulnerable. Additionally, inspect SDK containers for crafted extension points with paths containing '..' or unusual directory structures.

Impact Analysis

This vulnerability could allow an attacker to write, modify, or delete files outside the build directory, potentially leading to unauthorized code execution, data loss, or system corruption. It may also enable reading sensitive data or causing denial-of-service by crashing critical system files.

Compliance Impact

This vulnerability could potentially impact compliance with GDPR and HIPAA by allowing unauthorized file modifications or deletions on the host system. Attackers could write files outside intended directories, leading to unauthorized data access, modification, or destruction, which violates data integrity and confidentiality requirements in these regulations.

Mitigation Strategies

Upgrade Flatpak to version 1.18.1 or later. Avoid using untrusted SDKs for development. If upgrading is not possible, apply backported fixes from the flatpak-1.16.x branch for LTS distributions.

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