---
cve: "CVE-2026-39977"
severity: "HIGH"
cvss: 7.1
epss: "29%"
vendor: "flatpak"
kev: false
exploited: false
published: "2026-04-09 20:16:26"
tags: [cve, security, high]
source: tsecurity.de CVE-Dossier
exported: "2026-09-15T14:20:32+02:00"
---

# CVE-2026-39977

> 7.1 HIGH · 🧪 PoC

## Beschreibung

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-Vektor

```
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
```

| Metrik | Wert | Bewertung |
|---|---|---|
| AV Angriffsvektor | Netzwerk | bad |
| AC Komplexität | Gering | bad |
| PR Privilegien | Keine | bad |

## Patch verfügbar (OSV)

- 70421c1586e9046470c9a788fa3f3390d5431248 (Commit)

## Referenzen

- <https://github.com/flatpak/flatpak-builder/security/advisories/GHSA-6gm9-3g7m-3965>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-39977) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_