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Fencer Intel
critical 9.8

CVE-2026-96276 json

Flatpak: flatpak: arbitrary write in host context via flatpak build-init

published 3mo ago modified 6d ago also EUVD-2026-85343 , GHSA-8qxj-x646-phcm

Unreviewed: the maintainers' own advisory

Published by the maintainers on their GitHub repository flatpak/flatpak. 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
9.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 38%
public exploits
0
none known

Summary

If a malicious SDK container declares an extension point with a crafted `directory` path, and a developer runs `flatpak build-init --writable-sdk --sdk-extension` with that SDK, attacker-chosen files could be written outside the working directory, since the target path is resolved via a function that allows `..` traversal.

Patch / fix

  • flatpak Debian 13 1.16.6-1~deb13u2
  • flatpak Debian 14 1.18.1-1

debian advisories DEBIAN-CVE-2026-96276

  • flatpak SLES for SAP 15 SP5, SLES 15 SP5-LTSS, SLE High Performance Computing 15 SP5-LTSS +1 more 1.16.6-150500.3.21.1
  • flatpak SLES for SAP 15 SP6, SLES 15 SP6-LTSS, SLE Module for Desktop Applications 15 SP7 1.16.6-150600.3.12.1
  • flatpak SLES LTSS Extended Security 12 SP5, SLES 12 SP5-LTSS 1.4.2-3.15.1

suse advisories SUSE-SU-2026:5127-1SUSE-SU-2026:4944-1SUSE-SU-2026:4610-1

Is CVE-2026-96276 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-2026-96276 updated cvss 6.5

flatpak: flatpak: Arbitrary write in host context via flatpak build-init

  • Red Hat Enterprise Linux 7 flatpak, flatpak-libs, flatpak-builder, flatpak 1.18.0-1.el10 Red Hat Enterprise Linux 8 flatpak, flatpak-libs, flatpak-selinux, flatpak 1.18.0-1.el10, flatpak-session-helper Red Hat Enterprise Linux 9 flatpak, flatpak-libs, flatpak-selinux, flatpak 1.18.0-1.el10, flatpak-session-helper Red Hat Enterprise Linux 10 flatpak 1.18.0-1.el10
    affected: workaround, no fix available “Avoid using an non-trusted SDK for development/compilation.”

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
none
Automatable
yes
Technical impact
total
Assessed
last mo.

Exploit prediction

0.44% chance of exploitation in the next 30 days, higher than 38% of all scored CVEs (FIRST EPSS, 2026-11-11).

CVSS scores

assigned by version score vector
CNA 3.1 6.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N
CISA ADP 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CNA 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected products

  • Red Hat Red Hat Enterprise Linux 10
  • Red Hat Red Hat Enterprise Linux 7
  • Red Hat Red Hat Enterprise Linux 8
  • Red Hat Red Hat Enterprise Linux 9

Classification

Weakness
  • CWE-22 Improper Limitation of a Pathname to a Restricted Directory

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 published their own advisory on GitHub. Reviewed sources take precedence over it.