UBUNTU-CVE-2026-39977

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Source

https://ubuntu.com/security/CVE-2026-39977

Import Source

https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-39977.json

JSON Data

https://api.osv.dev/v1/vulns/UBUNTU-CVE-2026-39977

Upstream

CVE-2026-39977

Published

2026-04-09T20:16:00Z

Modified

2026-05-20T16:25:38Z

Severity

7.1 (High) CVSS_V4 - CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N CVSS Calculator
6.3 (Medium) CVSS_V3 - CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:C/C:H/I:N/A:N CVSS Calculator
Ubuntu - medium

Summary

[none]

Details

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.

References

Affected packages

Ubuntu:25.10 / flatpak-builder

Package

Name: flatpak-builder
Purl: pkg:deb/ubuntu/flatpak-builder?arch=source&distro=questing

Affected ranges

Type: ECOSYSTEM
Events: Introduced

0 Unknown introduced version / All previous versions are affected

Affected versions

1.*

1.4.4-2

1.4.4-2build1

1.4.5-1

1.4.6-2

Ecosystem specific

{
    "binaries": [
        {
            "binary_name": "flatpak-builder",
            "binary_version": "1.4.6-2"
        },
        {
            "binary_name": "flatpak-builder-tests",
            "binary_version": "1.4.6-2"
        }
    ]
}

Database specific

source

"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-39977.json"

Ubuntu:26.04:LTS / flatpak-builder