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.

The remote Fedora 44 host has a package installed that is affected by a vulnerability as referenced in the FEDORA-2026-5e62b78a0c advisory.

    This update includes a fix for [CVE-2026-39977](https://access.redhat.com/security/cve/CVE-2026-39977).
    See also: [the upstream advisory](https://github.com/flatpak/flatpak-     builder/security/advisories/GHSA-6gm9-3g7m-3965)

Tenable has extracted the preceding description block directly from the Fedora security advisory.

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

The remote Fedora 43 host has a package installed that is affected by a vulnerability as referenced in the FEDORA-2026-25ff246b4f advisory.

    This update includes a fix for [CVE-2026-39977](https://access.redhat.com/security/cve/CVE-2026-39977).
    See also: [the upstream advisory](https://github.com/flatpak/flatpak-     builder/security/advisories/GHSA-6gm9-3g7m-3965)

Tenable has extracted the preceding description block directly from the Fedora security advisory.

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

The remote Fedora 42 host has a package installed that is affected by a vulnerability as referenced in the FEDORA-2026-631b9d535c advisory.

    This update includes a fix for [CVE-2026-39977](https://access.redhat.com/security/cve/CVE-2026-39977).
    See also: [the upstream advisory](https://github.com/flatpak/flatpak-     builder/security/advisories/GHSA-6gm9-3g7m-3965)

Tenable has extracted the preceding description block directly from the Fedora security advisory.

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available.

  - 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. (CVE-2026-39977)

Note that Nessus relies on the presence of the package as reported by the vendor.

ID	Name	Product	Family	Severity
310213	Fedora 44 : flatpak-builder (2026-5e62b78a0c)	Nessus	Fedora Local Security Checks	high
310078	Fedora 43 : flatpak-builder (2026-25ff246b4f)	Nessus	Fedora Local Security Checks	high
310071	Fedora 42 : flatpak-builder (2026-631b9d535c)	Nessus	Fedora Local Security Checks	high
307042	Linux Distros Unpatched Vulnerability : CVE-2026-39977	Nessus	Misc.	high

Detections

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CVE-2026-39977

high

Tenable Plugins

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high

high

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