Flatpak: Twelve Vulnerabilities Disclosed in Deployment and OCI Handling
A batch of twelve vulnerabilities in Flatpak, disclosed between September 27-29, 2026, expose risks including path traversal, insecure file permissions, and OCI processing flaws.
Key findings
- Twelve vulnerabilities disclosed in Flatpak between Sep 27-29, 2026, impacting deployment, file handling, and OCI processing.
- Path traversal flaws allow malicious Flatpak apps to modify or delete host system files.
- Insecure file permissions and token handling create risks on multi-user systems.
- OCI image parsing vulnerabilities include heap overflows and arbitrary file linking.
- Process isolation bypasses and insecure extension handling also present security concerns.
On September 27-29, 2026, a batch of twelve vulnerabilities was disclosed in the Flatpak package management system. These vulnerabilities, ranging in severity from Low to High, primarily affect how Flatpak handles application deployments, file permissions, and OCI image parsing, potentially leading to denial-of-service conditions, unauthorized file access, and data corruption.
Several vulnerabilities center on path traversal issues during application deployment. CVE-2026-97024 and CVE-2026-97023 allow a malicious Flatpak application to manipulate files outside its designated sandbox. CVE-2026-97024 specifically targets the files/etc directory, enabling the emptying or replacement of critical host system files like /etc/passwd and /etc/machine-id during app installation or upgrades. Similarly, CVE-2026-97023 affects the export/bin directory, permitting the deletion of arbitrary host files, with deletions performed as root in system-wide installations.
Another group of vulnerabilities relates to insecure file permissions and token handling. CVE-2026-97026 highlights that Flatpak creates temporary child repository directories with world-writable permissions (0777), which could allow other local users to interfere with installations on multi-user systems. CVE-2026-97025 reveals that OCI repository authentication tokens are written with world-readable permissions (0644), potentially allowing other local users to impersonate the authenticated user against OCI repositories. Furthermore, CVE-2026-97029 points out that Flatpak's process ID namespace separation is insufficient, allowing sandboxed apps to send signals to processes outside the sandbox via kill(0, signal) or killpg(0, signal), leading to denial-of-service.
The OCI (Open Container Initiative) image handling is also implicated in several security flaws. CVE-2026-96280 involves heap buffer overflows due to incorrect size handling in the OCI delta stream parser, which can be triggered by an attacker-controlled OCI registry. CVE-2026-97029, while not directly OCI-related, touches on process management issues. CVE-2026-96279 allows a malicious OCI registry to hardlink arbitrary host files into the extraction directory during app installation or updates, potentially exposing sensitive files like /etc/shadow in system-wide installs. CVE-2026-96284 permits read access to files in the flatpak-system-helper context if a system OCI repository is configured, as the OCI code paths follow symlinks under user control.
Additional vulnerabilities include CVE-2026-97027, where Flatpak passes arbitrary vendor-extension keys unmodified, potentially leading to denial-of-service or influencing application behavior. CVE-2026-96283 describes a flaw where cancelling another user's pull operation via CancelPull does not actually stop the pull, making it impossible for the owning user to terminate it. Lastly, CVE-2026-96281 allows a local user to downgrade a system-wide Flatpak app by removing its remote ref, bypassing anti-downgrade checks.
These vulnerabilities underscore the importance of secure handling of file permissions, inter-process communication, and external data sources within sandboxing environments like Flatpak. Users are advised to update their Flatpak installations to the latest versions to mitigate these risks. The full impact and specific affected versions would typically be detailed in vendor advisories, which are crucial for understanding the precise scope of the threat.
The coordinated disclosure of these twelve vulnerabilities highlights a significant security event for the Flatpak ecosystem, impacting its core functionalities related to application deployment, system interaction, and remote repository management. The range of severity indicates that while some issues pose a moderate to high risk, even lower-severity flaws could be chained or exploited in specific multi-user or adversarial scenarios. Users and administrators should prioritize applying available patches and reviewing their Flatpak configurations, especially in shared or sensitive environments.
The vulnerabilities disclosed between September 27 and September 29, 2026, affect the Flatpak package management system. The issues span insecure file handling, process isolation bypasses, and vulnerabilities in OCI image processing, with severities ranging from Low to High.
Key findings include path traversal flaws allowing host file manipulation (CVE-2026-97024, CVE-2026-97023), insecure permissions for temporary directories and authentication tokens (CVE-2026-97026, CVE-2026-97025), and process namespace bypasses (CVE-2026-97029).
Vulnerabilities in OCI image handling, such as heap buffer overflows (CVE-2026-96280) and arbitrary file linking (CVE-2026-97029), were also disclosed.
Other issues include arbitrary vendor-extension key handling (CVE-2026-97027), inability to cancel pulls (CVE-2026-96283), and downgrade vulnerabilities (CVE-2026-96281).
The batch of twelve CVEs disclosed between September 27-29, 2026, reveals critical security weaknesses in Flatpak's handling of application deployments and OCI image processing.
Flatpak's process ID namespace separation fails to prevent external process termination via kill(0, signal) or killpg(0, signal) calls.
Path traversal vulnerabilities in Flatpak's handling of app deployment directories allow for the deletion or modification of host system files.
Insecure file permissions for temporary directories and OCI authentication tokens pose risks on multi-user systems.
Heap buffer overflows and arbitrary file linking vulnerabilities exist within Flatpak's OCI image parsing and extraction mechanisms.
The disclosure includes flaws related to arbitrary vendor-extension key handling and the inability to properly cancel ongoing pull operations.