CVE-2026-39977: CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') in flatpak flatpak-builder
flatpak-builder is a tool to build flatpaks from source. From 1.4.5 to before 1.4.8, the license-files manifest key takes an array of paths to user defined licence files relative to the source directory of the module. The paths from that array are resolved using g_file_resolve_relative_path() and validated to stay inside the source directory using two checks - g_file_get_relative_path() which does not resolve symlinks and g_file_query_file_type() with G_FILE_QUERY_INFO_NOFOLLOW_SYMLINKS which only applies to the final path component. The copy operation runs on host. This can be exploited by using a crafted manifest and/or source to read arbitrary files from the host and capture them into the build output. This vulnerability is fixed in 1.4.8.
AI Analysis
Technical Summary
flatpak-builder versions from 1.4.5 up to but not including 1.4.8 contain a path traversal vulnerability (CWE-22) in the handling of the license-files manifest key. The tool resolves license file paths relative to the source directory but uses insufficient checks that do not properly resolve symlinks or fully validate the path containment. This flaw allows an attacker to craft manifests and/or source files that cause arbitrary host files to be read and copied into the build output. The vulnerability is addressed in flatpak-builder 1.4.8.
Potential Impact
An attacker can exploit this vulnerability to read arbitrary files on the host system during the build process and include them in the build output. This could lead to unauthorized disclosure of sensitive host files. There is no indication of privilege escalation or code execution from the provided data.
Mitigation Recommendations
This vulnerability is fixed in flatpak-builder version 1.4.8. Users should upgrade to version 1.4.8 or later to remediate this issue. Patch status is not explicitly confirmed in the vendor advisory content provided, but the description states the issue is fixed in 1.4.8. No other mitigation or temporary fix is indicated.
CVE-2026-39977: CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') in flatpak flatpak-builder
Description
flatpak-builder is a tool to build flatpaks from source. From 1.4.5 to before 1.4.8, the license-files manifest key takes an array of paths to user defined licence files relative to the source directory of the module. The paths from that array are resolved using g_file_resolve_relative_path() and validated to stay inside the source directory using two checks - g_file_get_relative_path() which does not resolve symlinks and g_file_query_file_type() with G_FILE_QUERY_INFO_NOFOLLOW_SYMLINKS which only applies to the final path component. The copy operation runs on host. This can be exploited by using a crafted manifest and/or source to read arbitrary files from the host and capture them into the build output. This vulnerability is fixed in 1.4.8.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
flatpak-builder versions from 1.4.5 up to but not including 1.4.8 contain a path traversal vulnerability (CWE-22) in the handling of the license-files manifest key. The tool resolves license file paths relative to the source directory but uses insufficient checks that do not properly resolve symlinks or fully validate the path containment. This flaw allows an attacker to craft manifests and/or source files that cause arbitrary host files to be read and copied into the build output. The vulnerability is addressed in flatpak-builder 1.4.8.
Potential Impact
An attacker can exploit this vulnerability to read arbitrary files on the host system during the build process and include them in the build output. This could lead to unauthorized disclosure of sensitive host files. There is no indication of privilege escalation or code execution from the provided data.
Mitigation Recommendations
This vulnerability is fixed in flatpak-builder version 1.4.8. Users should upgrade to version 1.4.8 or later to remediate this issue. Patch status is not explicitly confirmed in the vendor advisory content provided, but the description states the issue is fixed in 1.4.8. No other mitigation or temporary fix is indicated.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-04-08T00:01:47.628Z
- Cvss Version
- 4.0
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 69d7ff941cc7ad14da10e9db
Added to database: 4/9/2026, 7:35:48 PM
Last enriched: 4/9/2026, 7:50:44 PM
Last updated: 4/10/2026, 8:15:30 AM
Views: 13
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