CVE-2026-39977

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.

CVSS v3 6.3 MEDIUM

6.3^/10

CVSS v3 : MEDIUM

Vector :

Exploitability : 1.8 / Impact : 4.0

Attack Vector LOCAL

Attack Complexity LOW

Privileges Required NONE

User Interaction REQUIRED

Confidentiality Impact HIGH

Integrity Impact NONE

Availability Impact NONE

Scope CHANGED

References

Link	Resource
https://github.com/flatpak/flatpak-builder/security/advisories/GHSA-6gm9-3g7m-3965	Exploit Vendor Advisory

Configurations

Configuration 1 (hide)

cpe:2.3:a:flatpak:flatpak-builder:*:*:*:*:*:*:*:*

History

16 Apr 2026, 20:52

Type	Values Removed	Values Added
CPE		cpe:2.3:a:flatpak:flatpak-builder::::::::
First Time		Flatpak Flatpak flatpak-builder
References	~~() https://github.com/flatpak/flatpak-builder/security/advisories/GHSA-6gm9-3g7m-3965 -~~	() https://github.com/flatpak/flatpak-builder/security/advisories/GHSA-6gm9-3g7m-3965 - Exploit, Vendor Advisory
CVSS	v2 : ~~unknown~~ v3 : ~~unknown~~	v2 : unknown v3 : 6.3

09 Apr 2026, 20:16

Type	Values Removed	Values Added
New CVE

Information

Published : 2026-04-09 20:16

Updated : 2026-04-16 20:52

NVD link : CVE-2026-39977

Mitre link : CVE-2026-39977

CVE.ORG link : CVE-2026-39977

JSON object : View

Products Affected

flatpak

flatpak-builder

CWE

CWE-22

Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')

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