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Fencer Vulns
high 7.4

CVE-2026-90616 json

In Flatpak before 1.18.1, a malicious sandboxed app can obtain arbitrary read and write access to files on the host, which can be escalated…

published 2026-09-12 57 d ago modified 2026-09-22 47 d ago also EUVD-2026-76911

cvss
7.4
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 7%
public exploits
0
none known

Summary

In Flatpak before 1.18.1, a malicious sandboxed app can obtain arbitrary read and write access to files on the host, which can be escalated to arbitrary code execution on the host, a different vulnerability than CVE-2026-76925. Flatpak creates a few app data directories (e.g., /var/cache, /var/data, /var/config, and /var/tmp) in every sandbox on every app launch where, in some cases, components of the path are attacker-controlled. Missing symlink protection can redirect the directories. Some of these directories are bind-mounted by Flatpak by passing the path (e.g., /home/user/.var/app/APP_ID/cache/tmp), which contains attacker-controlled directories (tmp) to bwrap --bind SRC DST. bwrap passes the path on to the kernel, which then follows symlinks. A malicious symlink can point to arbitrary locations on the host and it will become mounted inside the sandbox.

Patch / fix

  • Flatpak Flatpak 1.18.1
  • flatpak Debian 13 1.16.6-1~deb13u3
  • flatpak Debian 14 1.18.1-1

debian advisories DEBIAN-CVE-2026-90616

  • flatpak RHEL 8 1.12.9-7.el8_10
  • flatpak-libs RHEL 8 1.12.9-7.el8_10
  • flatpak-selinux RHEL 8 1.12.9-7.el8_10
  • flatpak-session-helper RHEL 8 1.12.9-7.el8_10
  • flatpak RHEL 10.2 1.16.0-9.el10_2.4
  • flatpak-libs RHEL 10.2 1.16.0-9.el10_2.4
  • flatpak-selinux RHEL 10.2 1.16.0-9.el10_2.4
  • flatpak-session-helper RHEL 10.2 1.16.0-9.el10_2.4

red hat advisories RHSA-2026:80687RHSA-2026:80498RHSA-2026:80497

  • 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

  • flatpak AlmaLinux 9 1.12.9-4.el9_8.4
  • flatpak-libs AlmaLinux 9 1.12.9-4.el9_8.4
  • flatpak-selinux AlmaLinux 9 1.12.9-4.el9_8.4
  • flatpak-session-helper AlmaLinux 9 1.12.9-4.el9_8.4
  • flatpak AlmaLinux 10 1.16.0-9.el10_2.4
  • flatpak-libs AlmaLinux 10 1.16.0-9.el10_2.4
  • flatpak-selinux AlmaLinux 10 1.16.0-9.el10_2.4
  • flatpak-session-helper AlmaLinux 10 1.16.0-9.el10_2.4

almalinux advisories ALSA-2026:80497ALSA-2026:80498ALSA-2026:80687

  • flatpak Rocky Linux 10 1.16.0-9.el10_2.4
  • flatpak Rocky Linux 9 1.12.9-4.el9_8.4
  • flatpak Rocky Linux 8 1.12.9-7.el8_10

rocky linux advisories RLSA-2026:80498RLSA-2026:80497RLSA-2026:80687

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-2026-90616 updated cvss 7.8

flatpak: Flatpak: Arbitrary code execution via missing symlink protection

  • Red Hat Enterprise Linux 7 flatpak, flatpak-libs, flatpak-builder
    affected: workaround, no fix available
  • Red Hat CodeReady Linux Builder EUS (v.9.6) flatpak 1.12.9-4.el9_6.5, flatpak-session-helper 1.12.9-4.el9_6.5
    fixed: vendor fix RHSA-2026:89733
  • Red Hat Enterprise Linux AppStream (v. 8) flatpak 1.12.9-7.el8_10, flatpak-libs 1.12.9-7.el8_10, flatpak-selinux 1.12.9-7.el8_10, flatpak-session-helper 1.12.9-7.el8_10
    fixed: vendor fix RHSA-2026:80687
  • Red Hat Enterprise Linux AppStream (v. 9) flatpak 1.12.9-4.el9_8.4, flatpak-libs 1.12.9-4.el9_8.4, flatpak-selinux 1.12.9-4.el9_8.4, flatpak-session-helper 1.12.9-4.el9_8.4
    fixed: vendor fix RHSA-2026:80497
  • Red Hat Enterprise Linux AppStream (v. 10) flatpak 1.16.0-9.el10_2.4, flatpak-libs 1.16.0-9.el10_2.4, flatpak-selinux 1.16.0-9.el10_2.4, flatpak-session-helper 1.16.0-9.el10_2.4
    fixed: vendor fix RHSA-2026:80498
  • Red Hat Enterprise Linux AppStream AUS (v.8.6) flatpak 1.12.9-1.el8_6.1, flatpak-libs 1.12.9-1.el8_6.1, flatpak-selinux 1.12.9-1.el8_6.1, flatpak-session-helper 1.12.9-1.el8_6.1
    fixed: vendor fix RHSA-2026:95493
  • Red Hat Enterprise Linux AppStream E4S (v.9.2) flatpak 1.12.7-5.el9_2.5, flatpak-libs 1.12.7-5.el9_2.5, flatpak-selinux 1.12.7-5.el9_2.5, flatpak-session-helper 1.12.7-5.el9_2.5
    fixed: vendor fix RHSA-2026:92369
  • Red Hat Enterprise Linux AppStream E4S (v.9.4) flatpak 1.12.9-3.el9_4.5, flatpak-libs 1.12.9-3.el9_4.5, flatpak-selinux 1.12.9-3.el9_4.5, flatpak-session-helper 1.12.9-3.el9_4.5
    fixed: vendor fix RHSA-2026:90364
show 7 more
  • Red Hat Enterprise Linux AppStream EUS (v. 10.0) flatpak 1.16.0-5.el10_0.6, flatpak-libs 1.16.0-5.el10_0.6, flatpak-selinux 1.16.0-5.el10_0.6, flatpak-session-helper 1.16.0-5.el10_0.6
    fixed: vendor fix RHSA-2026:92221
  • Red Hat Enterprise Linux AppStream EUS (v.9.6) flatpak 1.12.9-4.el9_6.5, flatpak-libs 1.12.9-4.el9_6.5, flatpak-selinux 1.12.9-4.el9_6.5, flatpak-session-helper 1.12.9-4.el9_6.5
    fixed: vendor fix RHSA-2026:89733
  • Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.6) flatpak 1.12.9-1.el8_6.1, flatpak-libs 1.12.9-1.el8_6.1, flatpak-selinux 1.12.9-1.el8_6.1, flatpak-session-helper 1.12.9-1.el8_6.1
    fixed: vendor fix RHSA-2026:95493
  • Red Hat Enterprise Linux CodeReady Linux Builder (v. 9) flatpak 1.12.9-4.el9_8.4, flatpak-session-helper 1.12.9-4.el9_8.4
    fixed: vendor fix RHSA-2026:80497
  • Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) flatpak-devel 1.16.0-9.el10_2.4, flatpak-debuginfo 1.16.0-9.el10_2.4, flatpak-debugsource 1.16.0-9.el10_2.4, flatpak-libs-debuginfo 1.16.0-9.el10_2.4, flatpak-tests-debuginfo 1.16.0-9.el10_2.4, flatpak-session-helper-debuginfo 1.16.0-9.el10_2.4
    fixed: vendor fix RHSA-2026:80498
  • Red Hat Enterprise Linux CodeReady Linux Builder EUS (v. 10.0) flatpak-devel 1.16.0-5.el10_0.6, flatpak-debuginfo 1.16.0-5.el10_0.6, flatpak-debugsource 1.16.0-5.el10_0.6, flatpak-libs-debuginfo 1.16.0-5.el10_0.6, flatpak-tests-debuginfo 1.16.0-5.el10_0.6, flatpak-session-helper-debuginfo 1.16.0-5.el10_0.6
    fixed: vendor fix RHSA-2026:92221
  • Red Hat Enterprise Linux CRB (v. 8) flatpak 1.12.9-7.el8_10, flatpak-session-helper 1.12.9-7.el8_10
    fixed: vendor fix RHSA-2026:80687

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
no
Technical impact
total
Assessed
55 d ago

Exploit prediction

0.18% chance of exploitation in the next 30 days, higher than 7% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 7.4 CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected products

  • Flatpak Flatpak

Classification

Weakness
  • CWE-61 UNIX Symbolic Link (Symlink) Following

References

Sources

Fencer Vulns 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.