CVE-2026-23950
node-tar,a Tar for Node.js, has a race condition vulnerability in versions up to and including 7.5.3.
Does this matter?
Lower severity and a low EPSS score (0.24%). Track it; it rarely justifies an emergency change on its own.
Description
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.
- CVSS 3.1
- 5.9 MEDIUMCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N
- EPSS
- 0.24% probability · 15th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-176, CWE-352, CWE-367
- Affected
- isaacs/tar
- Source
- security-advisories@github.com
References
- https://github.com/isaacs/node-tar/commit/3b1abfae650056edfabcbe0a0df5954d390521e6Patch
- https://github.com/isaacs/node-tar/security/advisories/GHSA-r6q2-hw4h-h46wExploit, Mitigation, Vendor Advisory
- https://access.redhat.com/errata/RHSA-2026:18480
- https://access.redhat.com/errata/RHSA-2026:18868
- https://access.redhat.com/errata/RHSA-2026:2144
- https://access.redhat.com/errata/RHSA-2026:2926
- https://access.redhat.com/errata/RHSA-2026:6192
- https://access.redhat.com/security/cve/CVE-2026-23950
- https://bugzilla.redhat.com/show_bug.cgi?id=2431036
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-23950.json
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.