# CVE-2026-97026: Flatpak: flatpak: world-writable temporary child repositories in system-helper cache path

Status: published. Published: 2026-09-28. Updated: 2026-11-06.

Flatpak creates temporary child repository directories under the user cache with world-writable permissions (0777). On multi-user systems with a permissive umask, other local users could read or modify the temporary directory used while installing apps or runtimes, potentially causing installation failures (denial of service); tampered content would fail signature/digest verification rather than being trusted.

## Remediation

- workaround: Set a umask that does not allow other users to write to the cache directory, for example: umask 022.

Note that a umask that does not allow read/exec access by all (for example 027 or 077) will prevent the flatpak-system-helper from reading the temporary directory directly, resulting in falling back to copying the repository inefficiently, with a warning. (source: CNA: redhat)

## Affected products and versions

- Red Hat / Red Hat Enterprise Linux 10 (flatpak): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 7 (flatpak): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 8 (flatpak): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 9 (flatpak): Version range not reported. Source: CNA: redhat

## Severity and prioritization

- CVSS 3.1: 3.9 (low); CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:L/I:N/A:L; source: CNA: redhat

- CISA KEV: No listing in collected sources

- EPSS: 0.10% as of 2026-11-06; percentile 1.04%

- SSVC: exploitation none; automatable no; technical impact partial; source ADP: CISA-ADP

- Weaknesses: CWE-378

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://access.redhat.com/security/cve/CVE-2026-97026 (CNA: redhat; vdb-entry, x_refsource_REDHAT)

- https://bugzilla.redhat.com/show_bug.cgi?id=2542637 (CNA: redhat; issue-tracking, x_refsource_REDHAT)

- https://github.com/flatpak/flatpak/security/advisories/GHSA-r9w3-qx54-qvc8 (CNA: redhat)

## Provenance

- CNA: redhat: https://www.cve.org/CVERecord?id=CVE-2026-97026; retrieved 2026-11-06; source updated 2026-11-06

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-97026; retrieved 2026-11-06; source updated Not reported

Revision: 4c50c85ba5a6f2f5a8b7204676a08d001e052eb486eb81e3d6990cd9a89ef7e6

Canonical: https://y2.dev/cve/CVE-2026-97026

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