Reference page — cumulative record through Sunday, October 4, 2026 UTC. Reference pages update as the archive grows; only dated daily editions are immutable pages of record.
CVE-2026-23950
isaacs node-tar — node-tar has Race Condition in Path Reservations via Unicode Ligature Collisions on macOS APFS
AV AC PR UI S C I A CVSS EPSS %ile KEV
N H N N U N H N 5.9 .0026 15.8 —
AFFECTED
Product Versions Fixed
node-tar < 7.5.4 – —
TIMELINE
Jan 19 Reserved by GitHub_M
Jan 20 Published (CNA: GitHub_M)
Aug 24 EXPLOIT PUBLISHED — CVE-2026-23950 (isaacs node-tar). Public exploit reference added.
Aug 24 RESCORED — CVE-2026-23950 (isaacs node-tar). CVSS 8.8 → 5.9 (NVD).
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.
Lifecycle
Complete event history — 4 events, chronological
| Date | Event | Detail |
|---|
| January 19, 2026 | Reserved | Reserved by GitHub_M |
| January 20, 2026 | Published | Published (CNA: GitHub_M) |
| August 24, 2026 | EXPLOIT PUBLISHED | EXPLOIT PUBLISHED — CVE-2026-23950 (isaacs node-tar). Public exploit reference added. |
| August 24, 2026 | RESCORED | RESCORED — CVE-2026-23950 (isaacs node-tar). CVSS 8.8 → 5.9 (NVD). |
Affected
Affected products and packages — 1 row
| Vendor | Product / Package | Ecosystem | Version introduced | Fixed |
|---|
| isaacs | node-tar | — | < 7.5.4 | — |
About this page
This is a reference page, not a dated page of record. It assembles the complete lifecycle of CVE-2026-23950 from the CVE Program record, NVD enrichment, the CISA KEV catalog, EPSS, and OSV advisories. The box score's numbers (CVSS, EPSS, KEV status) are current as of Sunday, October 4, 2026 UTC and are re-derived as the archive grows; only dated daily editions are immutable pages of record. The authoritative source for this identifier is cve.org.
