Flatpak: UNIX Symbolic Link (Symlink) Following
CVE-2026-96808 is a high-severity UNIX symbolic link (symlink) following vulnerability in Flatpak, with a CVSS 3.1 base score of 7.4 out of 10. It can be exploited with local access to the system by an unauthenticated attacker, without any action from a user. The record lists version 1.18.1 as the first without the flaw, so updating Flatpak to that release or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.11% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update Flatpak to 1.18.1 or a later version.
- Read the advisory on github.com for workarounds and exact fixed builds.
Affected products and versions
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- LocalThe attacker needs local access or must trick a user into running something.
- Attack complexity
- HighSuccess depends on conditions outside the attacker's control.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H. Scored by CNA (mitre.org).
Official description
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.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: UNIX Symbolic Link (Symlink) Following
The product, when opening a file or directory, does not sufficiently account for when the file is a symbolic link that resolves to a target outside of the intended control sphere. This could allow an attacker to cause the product to operate on unauthorized files.
How developers prevent this class of flaw
- Symbolic link attacks often occur when a program creates a tmp directory that stores files/links. Access to the directory should be restricted to the program as to prevent attackers from manipulating the files.
- Follow the principle of least privilege when assigning access rights to entities in a software system. Denying access to a file can prevent an attacker from replacing that file with a link to a sensitive file. Ensure good compartmentalization in the system to provide protected areas that can be trusted.
More UNIX Symbolic Link (Symlink) Following vulnerabilities (CWE-61)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Other vulnerabilities in Flatpak
- 7.2 High severity
- 7.4 High severity
- 7.5 High severity
- 10.0 Critical severity
- 10.0 Critical severity
- 8.4 High severity
Recent UNIX Symbolic Link (Symlink) Following vulnerabilities
- 9.8 Critical severity
- 7.8 High severity
- 7.3 High severity
- 7.1 High severity
- 8.2 High severity
- 8.8 High severity
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