CVE-2026-21636 [Critical] | Privilege Escalation in Node.js

A flaw in Node.js's permission model allows Unix Domain Socket (UDS) connections to bypass network restrictions when `--permission` is enabled. Even without `--allow-net`, attacker-controlled inputs (such as URLs or socketPath options) can connect to arbitrary local sockets via net, tls, or undici/fetch. This breaks the intended security boundary of the permission model and enables access to privileged local services, potentially leading to privilege escalation, data exposure, or local code execution. * The issue affects users of the Node.js permission model on version v25. In the moment of this vulnerability, network permissions (`--allow-net`) are still in the experimental phase.

#	Date	Old EPSS score	New EPSS score	Delta (New - Old)
1	2026-01-21	—	0.02%	—

Date

Old EPSS score

New EPSS score

Delta (New - Old)

2026-01-21

—

0.02%

—

Base score	Version	Severity	Vector	Exploitability	Impact	Score source
10.0	3.1	CRITICAL	`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H` 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:N) Nobody has to click “OK” or open a trap file; it can work without a victim helping. Scope (S:C) Breaking this can reach past the original component and bite other resources—bigger blast radius. Confidentiality (C:H) Serious risk that confidential data gets exposed in a big way. Integrity (I:H) They could widely tamper with or forge data—trust in the data is badly hurt. Availability (A:H) Could take the service down hard or make it unusable for people who depend on it.	3.9	6.0	[email protected]
5.8	3.0	MEDIUM	`CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:N/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: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:N) Nobody has to click “OK” or open a trap file; it can work without a victim helping. 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:N) Data isn’t meaningfully altered or forged. Availability (A:N) Service keeps running; no real outage angle.	3.9	1.4	[email protected]

Base score

Version

Severity

Vector

Exploitability

Impact

Score source

10.0

3.1

CRITICAL

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H 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:N): Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:C): Breaking this can reach past the original component and bite other resources—bigger blast radius.
Confidentiality (C:H): Serious risk that confidential data gets exposed in a big way.
Integrity (I:H): They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H): Could take the service down hard or make it unusable for people who depend on it.

3.9

6.0

[email protected]

5.8

3.0

MEDIUM

CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:N/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: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:N): Nobody has to click “OK” or open a trap file; it can work without a victim helping.
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:N): Data isn’t meaningfully altered or forged.
Availability (A:N): Service keeps running; no real outage angle.

3.9

1.4

[email protected]

OS Trackers for CVE-2026-21636

vendor	priority	summary	link
`debian`	unimportant	CVE-2026-21636 unimportant priority: Debian including 1 source packages (nodejs), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5.	https://security-tracker.debian.org/tracker/CVE-2026-21636
`redhat`	medium	—	https://access.redhat.com/security/cve/CVE-2026-21636
`suse`	high	CVE-2026-21636 severity important: SUSE including 33 source package names (corepack22, nodejs10, …), 129 product×package rows across 18 product lines (SUSE Linux Enterprise High Performance Computing 15 SP4-LTSS, SUSE Linux Enterprise High Performance Computing 15 SP5-LTSS, … (18 product lines)): Known Not Affected 129.	https://www.suse.com/security/cve/CVE-2026-21636/
`ubuntu`	medium	CVE-2026-21636 medium priority: Ubuntu including 1 source packages (nodejs), 9 status rows across 9 suites (bionic, focal, jammy, noble, plucky, questing, trusty, upstream, xenial): needs-triage 7, ignored 1, not-affected 1.	https://ubuntu.com/security/CVE-2026-21636

Affected software / configurations for CVE-2026-21636

Vendor	Product	Version	Raw CPE
nodejs	node.js	>= 25.0.0, < 25.3.0	cpe:2.3:a:nodejs:node.js:::::-:::*

References for CVE-2026-21636

URL	Tags
https://nodejs.org/en/blog/vulnerability/december-2025-security-releases	Vendor Advisory Release Notes

URL

CVE-2026-21636

Exploit prediction scoring system (EPSS) score for CVE-2026-21636

Common vulnerability scoring system (CVSS) metrics for CVE-2026-21636

Weakness enumeration for CVE-2026-21636

OS Trackers for CVE-2026-21636

Affected software / configurations for CVE-2026-21636

References for CVE-2026-21636