CVE-2026-23950 [High] | Security Bypass in Tar

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.

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#	Date	Old EPSS score	New EPSS score	Delta (New - Old)
1	2026-01-20	—	0.01%	—

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2026-01-20

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0.01%

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Base score	Version	Severity	Vector	Exploitability	Impact	Score source
8.8	3.1	HIGH	`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:H/A:L` Click to expand Attack vector (AV:N) Could be attacked over the internet or any normal routed network—not just someone sitting at the machine. Attack complexity (AC:L) Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup. Privileges required (PR:N) No account or special rights needed—anonymous or random user is enough. User interaction (UI:R) A real person has to do something—click, install, enable—otherwise it doesn’t land. Scope (S:C) Breaking this can reach past the original component and bite other resources—bigger blast radius. Confidentiality (C:L) Some sensitive info could get out, but not a total data dump. Integrity (I:H) They could widely tamper with or forge data—trust in the data is badly hurt. Availability (A:L) Might cause slowdowns, glitches, or partial disruption—not a full brick.	2.8	5.3	[email protected]
5.9	3.1	MEDIUM	`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N` Click to expand Attack vector (AV:N) Could be attacked over the internet or any normal routed network—not just someone sitting at the machine. Attack complexity (AC:H) Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work. Privileges required (PR:N) No account or special rights needed—anonymous or random user is enough. User interaction (UI:N) Nobody has to click “OK” or open a trap file; it can work without a victim helping. Scope (S:U) Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems. Confidentiality (C:N) Doesn’t really leak secrets in a meaningful way. Integrity (I:H) They could widely tamper with or forge data—trust in the data is badly hurt. Availability (A:N) Service keeps running; no real outage angle.	2.2	3.6	[email protected]

Base score

Version

Severity

Vector

Exploitability

Impact

Score source

8.8

3.1

HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:H/A:L Click to expand

Attack vector (AV:N): Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L): Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N): No account or special rights needed—anonymous or random user is enough.
User interaction (UI:R): A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:C): Breaking this can reach past the original component and bite other resources—bigger blast radius.
Confidentiality (C:L): Some sensitive info could get out, but not a total data dump.
Integrity (I:H): They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:L): Might cause slowdowns, glitches, or partial disruption—not a full brick.

2.8

5.3

[email protected]

5.9

3.1

MEDIUM

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N Click to expand

Attack vector (AV:N): Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:H): Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:N): No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N): Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U): Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N): Doesn’t really leak secrets in a meaningful way.
Integrity (I:H): They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:N): Service keeps running; no real outage angle.

2.2

3.6

[email protected]

Weakness enumeration for CVE-2026-23950

OS Trackers for CVE-2026-23950

vendor	priority	summary	link
`alpine`	—	CVE-2026-23950: 1 source package rows (npm); 13 state rows across 3 repos (3.23-community, edge-community, edge-main); fixed 1, open 12.	https://security.alpinelinux.org/vuln/CVE-2026-23950
`debian`	unimportant	CVE-2026-23950 unimportant priority: Debian including 1 source packages (node-tar), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 3, open 2.	https://security-tracker.debian.org/tracker/CVE-2026-23950
`redhat`	high	—	https://access.redhat.com/security/cve/CVE-2026-23950
`ubuntu`	medium	CVE-2026-23950 medium priority: Ubuntu including 1 source packages (node-tar), 8 status rows across 8 suites (bionic, focal, jammy, noble, questing, trusty, upstream, xenial): needs-triage 8.	https://ubuntu.com/security/CVE-2026-23950

Affected software / configurations for CVE-2026-23950

Vendor	Product	Version	Raw CPE
isaacs	tar	< 7.5.4	cpe:2.3:a:isaacs:tar::::::node.js::*

References for CVE-2026-23950

URL	Tags
https://github.com/isaacs/node-tar/commit/3b1abfae650056edfabcbe0a0df5954d390521e6	Patch
https://github.com/isaacs/node-tar/security/advisories/GHSA-r6q2-hw4h-h46w	Exploit Mitigation Vendor Advisory

URL

CVE-2026-23950 | node-tar has Race Condition in Path Reservations via Unicode Ligature Collisions on macOS APFS

Public exploit references (Exploit-DB) for CVE-2026-23950

Exploit prediction scoring system (EPSS) score for CVE-2026-23950

Common vulnerability scoring system (CVSS) metrics for CVE-2026-23950

Weakness enumeration for CVE-2026-23950

GitHub Security Advisory for CVE-2026-23950

OS Trackers for CVE-2026-23950

Affected software / configurations for CVE-2026-23950

References for CVE-2026-23950