{"id":"UBUNTU-CVE-2026-23950","details":"node-tar,a Tar for Node.js, has a race condition vulnerability in versions up to and including 7.5.3. This is due to an incomplete handling of Unicode path collisions in the `path-reservations` system. On case-insensitive or normalization-insensitive filesystems (such as macOS APFS, In which it has been tested), the library fails to lock colliding paths (e.g., `ß` and `ss`), allowing them to be processed in parallel. This bypasses the library's internal concurrency safeguards and permits Symlink Poisoning attacks via race conditions. The library uses a `PathReservations` system to ensure that metadata checks and file operations for the same path are serialized. This prevents race conditions where one entry might clobber another concurrently. This is a Race Condition which enables Arbitrary File Overwrite. This vulnerability affects users and systems using node-tar on macOS (APFS/HFS+). Because of using `NFD` Unicode normalization (in which `ß` and `ss` are different), conflicting paths do not have their order properly preserved under filesystems that ignore Unicode normalization (e.g., APFS (in which `ß` causes an inode collision with `ss`)). This enables an attacker to circumvent internal parallelization locks (`PathReservations`) using conflicting filenames within a malicious tar archive. The patch in version 7.5.4 updates `path-reservations.js` to use a normalization form that matches the target filesystem's behavior (e.g., `NFKD`), followed by first `toLocaleLowerCase('en')` and then `toLocaleUpperCase('en')`. As a workaround, users who cannot upgrade promptly, and who are programmatically using `node-tar` to extract arbitrary tarball data should filter out all `SymbolicLink` entries (as npm does) to defend against arbitrary file writes via this file system entry name collision issue.","modified":"2026-02-23T06:57:45.298237Z","published":"2026-01-20T01:15:00Z","upstream":["CVE-2026-23950"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2026-23950"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2026-23950"},{"type":"REPORT","url":"https://github.com/isaacs/node-tar/security/advisories/GHSA-r6q2-hw4h-h46w"},{"type":"REPORT","url":"https://github.com/isaacs/node-tar/commit/3b1abfae650056edfabcbe0a0df5954d390521e6"},{"type":"REPORT","url":"https://github.com/isaacs/node-tar/commit/3b1abfae650056edfabcbe0a0df5954d390521e6"}],"affected":[{"package":{"name":"node-tar","ecosystem":"Ubuntu:Pro:14.04:LTS","purl":"pkg:deb/ubuntu/node-tar@0.1.18-1ubuntu0.1~esm1?arch=source&distro=esm-infra-legacy/trusty"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["0.1.18-1","0.1.18-1ubuntu0.1~esm1"],"ecosystem_specific":{"binaries":[{"binary_name":"node-tar","binary_version":"0.1.18-1ubuntu0.1~esm1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-23950.json"}},{"package":{"name":"node-tar","ecosystem":"Ubuntu:Pro:16.04:LTS","purl":"pkg:deb/ubuntu/node-tar@1.0.3-2ubuntu0.1~esm1?arch=source&distro=esm-apps/xenial"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.0.3-2","1.0.3-2ubuntu0.1~esm1"],"ecosystem_specific":{"binaries":[{"binary_name":"node-tar","binary_version":"1.0.3-2ubuntu0.1~esm1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-23950.json"}},{"package":{"name":"node-tar","ecosystem":"Ubuntu:18.04:LTS","purl":"pkg:deb/ubuntu/node-tar@2.2.1-1?arch=source&distro=bionic"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.2.1-1"],"ecosystem_specific":{"binaries":[{"binary_name":"node-tar","binary_version":"2.2.1-1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-23950.json"}},{"package":{"name":"node-tar","ecosystem":"Ubuntu:Pro:20.04:LTS","purl":"pkg:deb/ubuntu/node-tar@4.4.10+ds1-2ubuntu1+esm1?arch=source&distro=esm-apps/focal"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["4.4.10+ds1-2","4.4.10+ds1-2ubuntu1","4.4.10+ds1-2ubuntu1+esm1"],"ecosystem_specific":{"binaries":[{"binary_name":"node-tar","binary_version":"4.4.10+ds1-2ubuntu1+esm1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-23950.json"}},{"package":{"name":"node-tar","ecosystem":"Ubuntu:22.04:LTS","purl":"pkg:deb/ubuntu/node-tar@6.1.11+ds1+~cs6.0.6-1?arch=source&distro=jammy"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["6.1.7+~cs11.3.10-1","6.1.11+~cs11.3.10-1","6.1.11+ds1+~cs6.0.6-1"],"ecosystem_specific":{"binaries":[{"binary_name":"node-tar","binary_version":"6.1.11+ds1+~cs6.0.6-1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-23950.json"}},{"package":{"name":"node-tar","ecosystem":"Ubuntu:24.04:LTS","purl":"pkg:deb/ubuntu/node-tar@6.1.13+~cs7.0.5-3?arch=source&distro=noble"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["6.1.13+~cs7.0.5-1","6.1.13+~cs7.0.5-3"],"ecosystem_specific":{"binaries":[{"binary_name":"node-tar","binary_version":"6.1.13+~cs7.0.5-3"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-23950.json"}},{"package":{"name":"node-tar","ecosystem":"Ubuntu:25.10","purl":"pkg:deb/ubuntu/node-tar@6.2.1+~cs7.0.8-1?arch=source&distro=questing"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["6.2.1+~cs7.0.8-1"],"ecosystem_specific":{"binaries":[{"binary_name":"node-tar","binary_version":"6.2.1+~cs7.0.8-1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-23950.json"}}],"schema_version":"1.7.3","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:H/A:L"},{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N"},{"type":"Ubuntu","score":"medium"}]}