{"id":"UBUNTU-CVE-2026-64846","details":"Nix is a package manager for Linux and other Unix systems. Prior to 2.35.0, a malicious derivation executed with the recursive-nix experimental feature can exploit a time-of-check/time-of-use race involving final symlink handling in the LocalStore restore path. The race can cause writeFile to follow a substituted final symlink when opening a path with O_TRUNC instead of enforcing FinalSymlink::DontFollow, allowing the Nix process or nix-daemon to create or truncate an empty file outside the build sandbox with the daemon user's permissions. The primitive does not provide arbitrary-content writes and requires winning the race. This issue is fixed in version 2.35.0.","modified":"2026-09-02T19:35:33.354993792Z","published":"2026-08-20T17:19:00Z","upstream":["CVE-2026-64846"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2026-64846"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2026-64846"}],"affected":[{"package":{"name":"nix","ecosystem":"Ubuntu:Pro:22.04:LTS","purl":"pkg:deb/ubuntu/nix?arch=source&distro=esm-apps%2Fjammy"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.3.10+dfsg1-1","2.3.10+dfsg1-1build1","2.6.0+dfsg-2","2.6.0+dfsg-3","2.6.0+dfsg-3ubuntu0.1~esm1"],"ecosystem_specific":{"binaries":[{"binary_name":"nix-bin","binary_version":"2.6.0+dfsg-3ubuntu0.1~esm1"},{"binary_version":"2.6.0+dfsg-3ubuntu0.1~esm1","binary_name":"nix-setup-systemd"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-64846.json"}},{"package":{"name":"nix","ecosystem":"Ubuntu:Pro:24.04:LTS","purl":"pkg:deb/ubuntu/nix?arch=source&distro=esm-apps%2Fnoble"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.16.1+dfsg-3ubuntu1","2.18.1+dfsg-1ubuntu1","2.18.1+dfsg-1ubuntu2","2.18.1+dfsg-1ubuntu4","2.18.1+dfsg-1ubuntu5","2.18.1+dfsg-1ubuntu5+esm2"],"ecosystem_specific":{"binaries":[{"binary_version":"2.18.1+dfsg-1ubuntu5+esm2","binary_name":"nix-bin"},{"binary_name":"nix-setup-systemd","binary_version":"2.18.1+dfsg-1ubuntu5+esm2"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-64846.json"}},{"package":{"name":"nix","ecosystem":"Ubuntu:26.04:LTS","purl":"pkg:deb/ubuntu/nix?arch=source&distro=resolute"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.26.3+dfsg-1ubuntu4","2.26.3+dfsg-1ubuntu5","2.32.5+dfsg-1ubuntu3","2.32.5+dfsg-2ubuntu1","2.34.3+dfsg-1"],"ecosystem_specific":{"binaries":[{"binary_name":"nix-bin","binary_version":"2.34.3+dfsg-1"},{"binary_name":"nix-setup-systemd","binary_version":"2.34.3+dfsg-1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-64846.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:N/I:L/A:N"},{"type":"Ubuntu","score":"medium"}]}