CVE-2026-96808: flatpak UNIX Symbolic Link (Symlink) Following

Vulnerability summary

CVE-2026-96808 is a high (CVSS 7.4) UNIX Symbolic Link (Symlink) Following vulnerability in flatpak. EPSS estimates a 0.12% chance of exploitation in the next 30 days, higher than 1.6% of scored vulnerabilities.

Timeline

1. 23-09-2026
   PublishedVulnerability first disclosed.
2. 23-09-2026
   Last modifiedVulnerability information updated.

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.

• CWE-61UNIX Symbolic Link (Symlink) FollowingThe 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.