---
id: CVE-2026-96808
title: >-
  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 .
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 malic…
severity: high
cvss: 7.4
cvssVector: 'CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H'
cwe:
  - CWE-61
  - CWE-59
vendor: Flatpak
product: Flatpak
affected:
  - Flatpak < 1.18.1
published: '2026-09-23'
updated: '2026-09-24'
sourceUpdated: '2026-09-24T21:00:46.893'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-96808'
references:
  - url: 'https://github.com/flatpak/flatpak/security/advisories/GHSA-qrwq-7qwx-q9rp'
    label: cve@mitre.org
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-96808.json
  - url: 'https://access.redhat.com/security/cve/CVE-2026-96808'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2539569'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-96808'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-96808'
tags:
  - nvd
  - cve.org
  - csaf
  - vex
  - red-hat
epss: 0.00119
epssPercentile: 0.01587
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-09-23T18:22:36.969505Z'
scores:
  nvd: 7.4
  vendor: 7.8
ingestedAt: '2026-09-23T17:28:14.860Z'
---

## Overview

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.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

## Vendor advisories

- **Red Hat VEX** · Important · affected: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 7, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9 · no fix planned: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 7, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9 · updated 2026-09-23 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-96808.json)