CVE-2026-97029 [MEDIUM] – Flatpak’s process ID namespace separation does not prevent a sandboxed app’s kill(0, signa

Flatpak’s process ID namespace separation does not prevent a sandboxed app’s kill(0, signal) or killpg(0, signal) calls from reaching processes outside the sandbox that share the same process group. A malicious or compromised Flatpak app can use this to cause denial of service by terminating processes outside its sandbox, such as the desktop shell.