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Fencer Vulns
high 7.4

CVE-2026-96808 json

In Flatpak before 1.18.1, the revokefs writer, used by the flatpak-system-helper to receive repository data from unprivileged callers, vali…

published 2026-09-23 46 d ago modified 2026-09-24 45 d ago also EUVD-2026-85424

cvss
7.4
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.1%
EPSS 0.1% chance of exploitation in 30 days, percentile 1%
public exploits
0
none known

Summary

In Flatpak before 1.18.1, the revokefs writer, used by the flatpak-system-helper to receive repository data from unprivileged callers, validated file paths by rejecting literal .. components but did not prevent symlink traversal. A malicious local user in an active local session could obtain two revokefs sessions via the system helper, create a symlink in one session pointing into the other session's directory, and retain a file descriptor through that symlink. This allowed the attacker to modify files belonging to a different revokefs session after they had been validated and imported by the system helper. In particular, an attacker could use this to tamper with ostree commit objects in the system repository after they passed signature verification, enabling root-controlled file writes to attacker-chosen paths and local root privilege escalation.

Patch / fix

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

debian advisories DEBIAN-CVE-2026-96808

  • 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-2026-96808 updated cvss 7.8

flatpak: Flatpak: Local privilege escalation via symlink traversal in revokefs writer

  • 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
46 d ago

Exploit prediction

0.11% chance of exploitation in the next 30 days, higher than 1% 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.