# CVE-2026-86320: Flatpak-builder: host code execution via `git am` hook execution in patch source extraction (`use-git-am`)

Status: published. Published: 2026-09-17. Updated: 2026-11-11.

A flaw was found in flatpak-builder where Git hooks are not disabled when applying patch sources with use-git-am: true. An attacker who can provide a malicious source containing a Git post-applypatch hook can cause the hook to execute on the host during the build process, resulting in arbitrary code execution with the privileges of the user running flatpak-builder.

## Remediation

- workaround: Avoid using use-git-am: true when processing untrusted manifests or source material. Where untrusted builds are required, perform builds inside disposable virtual machines or other isolated environments. (source: CNA: redhat)

## Affected products and versions

- Red Hat / Red Hat Enterprise Linux 10 (flatpak-builder): ≥ 0:1.4.4-1.el10_2.1; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 10 (flatpak-builder): ≥ 0:1.4.7-1.el10_3.1; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 10.0 Extended Update Support (flatpak-builder): ≥ 0:1.4.4-1.el10_0.1; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 8 (flatpak-builder): ≥ 0:1.2.3-2.el8_10; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support (flatpak-builder): ≥ 0:1.0.9-4.el8_4; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On (flatpak-builder): ≥ 0:1.0.9-4.el8_4; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support (flatpak-builder): ≥ 0:1.0.9-4.el8_6; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-On (flatpak-builder): ≥ 0:1.0.9-4.el8_6; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 8.8 Telecommunications Update Service (flatpak-builder): ≥ 0:1.0.14-3.el8_8; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions (flatpak-builder): ≥ 0:1.0.14-3.el8_8; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 9 (flatpak-builder): ≥ 0:1.2.3-1.el9_8.1; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 9 (flatpak-builder): ≥ 0:1.2.3-1.el9_9.1; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions (flatpak-builder): ≥ 0:1.2.2-2.el9_2; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 9.4 Update Services for SAP Solutions (flatpak-builder): ≥ 0:1.2.3-2.el9_4; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 9.6 Extended Update Support (flatpak-builder): ≥ 0:1.2.3-1.el9_6.1; < * (unaffected, rpm). Source: CNA: redhat

## Severity and prioritization

- CVSS 3.1: 7.8 (high); CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H; source: CNA: redhat

- CISA KEV: No listing in collected sources

- EPSS: 0.30% as of 2026-11-10; percentile 22.81%

- SSVC: exploitation poc; automatable no; technical impact total; source ADP: CISA-ADP

- Weaknesses: CWE-94

## Exploit evidence

- exploit: https://bugzilla.redhat.com/show_bug.cgi?id=2471023 (ADP: CISA-ADP)
- exploit: https://github.com/flatpak/flatpak-builder/security/advisories/GHSA-j5p8-jgjc-f3xv (ADP: CISA-ADP)

## References

- https://access.redhat.com/errata/RHSA-2026:80495 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:80496 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:80973 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:84832 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:84833 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:84834 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:84842 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:86714 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:90896 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:92220 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:98536 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:98642 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/security/cve/CVE-2026-86320 (CNA: redhat; vdb-entry, x_refsource_REDHAT)

- https://bugzilla.redhat.com/show_bug.cgi?id=2471023 (CNA: redhat; issue-tracking, x_refsource_REDHAT)

- https://github.com/flatpak/flatpak-builder/security/advisories/GHSA-j5p8-jgjc-f3xv (CNA: redhat)

- https://bugzilla.redhat.com/show_bug.cgi?id=2471023 (ADP: CISA-ADP; exploit)

- https://github.com/flatpak/flatpak-builder/security/advisories/GHSA-j5p8-jgjc-f3xv (ADP: CISA-ADP; exploit)

## Provenance

- CNA: redhat: https://www.cve.org/CVERecord?id=CVE-2026-86320; retrieved 2026-11-11; source updated 2026-11-11

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-86320; retrieved 2026-11-11; source updated Not reported

Revision: f544f6cb21750f2954ed75ea59ce35fb2d1228e80b203a19e5aeaeeb2e953ebf

Canonical: https://y2.dev/cve/CVE-2026-86320

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