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Fencer Intel
high 7.8

CVE-2026-86320 json

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

published last mo. modified 14h ago also EUVD-2026-81387 , GHSA-j5p8-jgjc-f3xv

Unreviewed: the maintainers' own advisory

Published by the maintainers on their GitHub repository flatpak/flatpak-builder. GitHub has not reviewed it into the GitHub Advisory Database, so the affected packages and versions are the maintainers' word. Read the full advisory on GitHub.

cvss
7.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.3%
EPSS 0.3% chance of exploitation in 30 days, percentile 22%
public exploits
0
none known

Summary

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.

Patch / fix

  • Red Hat Red Hat Enterprise Linux 10 0:1.4.4-1.el10_2.1, 0:1.4.7-1.el10_3.1
  • Red Hat Red Hat Enterprise Linux 10.0 Extended Update Support 0:1.4.4-1.el10_0.1
  • Red Hat Red Hat Enterprise Linux 8 0:1.2.3-2.el8_10
  • Red Hat Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support 0:1.0.9-4.el8_4
  • Red Hat Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On 0:1.0.9-4.el8_4
  • Red Hat Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support 0:1.0.9-4.el8_6
  • Red Hat Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-On 0:1.0.9-4.el8_6
  • Red Hat Red Hat Enterprise Linux 8.8 Telecommunications Update Service 0:1.0.14-3.el8_8
  • Red Hat Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions 0:1.0.14-3.el8_8
  • Red Hat Red Hat Enterprise Linux 9 0:1.2.3-1.el9_8.1, 0:1.2.3-1.el9_9.1
  • Red Hat Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions 0:1.2.2-2.el9_2
  • Red Hat Red Hat Enterprise Linux 9.4 Update Services for SAP Solutions 0:1.2.3-2.el9_4
  • Red Hat Red Hat Enterprise Linux 9.6 Extended Update Support 0:1.2.3-1.el9_6.1
  • flatpak-builder Debian 14 1.4.11-1

debian advisories DEBIAN-CVE-2026-86320

  • flatpak-builder RHEL 8 1.2.3-2.el8_10
  • flatpak-builder RHEL 10.2 1.4.4-1.el10_2.1
  • flatpak-builder RHEL 9 1.2.3-1.el9_8.1
  • flatpak-builder RHEL 9.2 E4S 1.2.2-2.el9_2
  • flatpak-builder RHEL 9.6 EUS 1.2.3-1.el9_6.1
  • flatpak-builder enterprise linux eus 10.0 1.4.4-1.el10_0.1
  • flatpak-builder RHEL 9.4 E4S 1.2.3-2.el9_4

red hat advisories RHSA-2026:84842RHSA-2026:84833RHSA-2026:84834RHSA-2026:84832RHSA-2026:80973RHSA-2026:80495

  • flatpak-builder openSUSE Tumbleweed 1.4.12-1.1

opensuse advisories openSUSE-SU-2026:11845-1

  • flatpak-builder AlmaLinux 10 1.4.4-1.el10_2.1
  • flatpak-builder AlmaLinux 9 1.2.3-1.el9_8.1
  • flatpak-builder AlmaLinux 8 1.2.3-2.el8_10

almalinux advisories ALSA-2026:80495ALSA-2026:80496ALSA-2026:80973

  • flatpak-builder Rocky Linux 9 1.2.3-1.el9_8.1
  • flatpak-builder Rocky Linux 8 1.2.3-2.el8_10
  • flatpak-builder Rocky Linux 10 1.4.4-1.el10_2.1

rocky linux advisories RLSA-2026:98536RLSA-2026:80973RLSA-2026:80495RLSA-2026:80496

  • flatpak-builder Alpine 3.24 1.4.11-r0

alpine advisories ALPINE-CVE-2026-86320

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

Is CVE-2026-86320 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-86320 updated cvss 7.8

flatpak-builder: Host code execution via `git am` hook execution in patch source extraction (`use-git-am`)

  • Red Hat Enterprise Linux AppStream (v. 8) flatpak-builder 1.2.3-2.el8_10
    fixed: vendor fix RHSA-2026:80973
  • Red Hat Enterprise Linux AppStream (v. 9) flatpak-builder 1.2.3-1.el9_8.1, flatpak-builder 1.2.3-1.el9_9.1
    fixed: vendor fix RHSA-2026:80496
  • Red Hat Enterprise Linux AppStream (v. 10) flatpak-builder 1.4.4-1.el10_2.1, flatpak-builder 1.4.7-1.el10_3.1
    fixed: vendor fix RHSA-2026:80495
  • Red Hat Enterprise Linux AppStream AUS (v.8.4) flatpak-builder 1.0.9-4.el8_4
    fixed: vendor fix RHSA-2026:92220
  • Red Hat Enterprise Linux AppStream AUS (v.8.6) flatpak-builder 1.0.9-4.el8_6
    fixed: vendor fix RHSA-2026:90896
  • Red Hat Enterprise Linux AppStream E4S (v.8.8) flatpak-builder 1.0.14-3.el8_8
    fixed: vendor fix RHSA-2026:86714
  • Red Hat Enterprise Linux AppStream E4S (v.9.2) flatpak-builder 1.2.2-2.el9_2
    fixed: vendor fix RHSA-2026:84842
  • Red Hat Enterprise Linux AppStream E4S (v.9.4) flatpak-builder 1.2.3-2.el9_4
    fixed: vendor fix RHSA-2026:84832
show 5 more
  • Red Hat Enterprise Linux AppStream EUS (v. 10.0) flatpak-builder 1.4.4-1.el10_0.1
    fixed: vendor fix RHSA-2026:84834
  • Red Hat Enterprise Linux AppStream EUS (v.9.6) flatpak-builder 1.2.3-1.el9_6.1
    fixed: vendor fix RHSA-2026:84833
  • Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.4) flatpak-builder 1.0.9-4.el8_4
    fixed: vendor fix RHSA-2026:92220
  • Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.6) flatpak-builder 1.0.9-4.el8_6
    fixed: vendor fix RHSA-2026:90896
  • Red Hat Enterprise Linux AppStream TUS (v.8.8) flatpak-builder 1.0.14-3.el8_8
    fixed: vendor fix RHSA-2026:86714

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
total
Assessed
last mo.

Exploit prediction

0.30% chance of exploitation in the next 30 days, higher than 22% of all scored CVEs (FIRST EPSS, 2026-11-11).

Exploits and checks

  • bugzilla.redhat.com https://bugzilla.redhat.com/show_bug.cgi?id=2471023 referenced PoC, tagged "exploit" by a source, unverified
  • github.com https://github.com/flatpak/flatpak-builder/security/advisories/GHSA-j5p8-jgjc-f3xv referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 7.8 CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Affected products

  • Red Hat Red Hat Enterprise Linux 10
  • Red Hat Red Hat Enterprise Linux 10.0 Extended Update Support
  • Red Hat Red Hat Enterprise Linux 8
  • Red Hat Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support
  • Red Hat Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On
  • Red Hat Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support
  • Red Hat Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-On
  • Red Hat Red Hat Enterprise Linux 8.8 Telecommunications Update Service
  • Red Hat Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions
  • Red Hat Red Hat Enterprise Linux 9
  • Red Hat Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions
  • Red Hat Red Hat Enterprise Linux 9.4 Update Services for SAP Solutions
  • Red Hat Red Hat Enterprise Linux 9.6 Extended Update Support

Classification

Weakness
  • CWE-94 Improper Control of Generation of Code

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

The maintainers of flatpak/flatpak-builder published their own advisory on GitHub. Reviewed sources take precedence over it.