High Denial of service

CVE-2026-21637 — Uncontrolled Resource Consumption in Nodejs Node

A flaw in Node.js TLS error handling allows remote attackers to crash or exhaust resources of a TLS server when `pskCallback` or `ALPNCallback` are in use. Synchronous exceptions thrown during these callbacks bypass standard TLS error handling paths (tlsClientError and error), causing either immediate process termination or silent file descriptor leaks that eventually lead to denial of service. Because these callbacks process attacker-controlled input during the TLS handshake, a remote client can repeatedly trigger the issue. This vulnerability affects TLS servers using PSK or ALPN callbacks across Node.js versions where these callbacks throw without being safely wrapped.

Published Jan 20, 2026 · Updated Oct 13, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP · CNA: hackerone

Low

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.

How the score was calculated

EPSS 1.1% (30-day exploitation probability)+10
Technical severity (high)+6
Automatable exploitation (SSVC)+3

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation

Not confirmed

Not in CISA KEV — an absence of record, not proof it is unexploited.

EPSS FIRST

1.14%

ahead of 66% of scored CVEs · Oct 14, 2026

Affects

Nodejs

Node and 1 more

CVSS base

7.5

High · 3 source(s)

CISA SSVC assessment CISA

Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.

Exploitation

None

none · proof-of-concept · active

Automatable

Yes

can an attacker script the kill-chain steps

Technical impact

Partial

partial · total control of the vulnerable component

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

Identify exposed assets running the affected vendor/product/version combinations (Nodejs Node, Nodejs Node.js).
The attack is network-based and needs no privileges: restrict exposure (ACLs, VPN, WAF) until patched.
No fix documented in the sources: reduce exposure and monitor the vendor advisory.
Search available logs for exploit probes matching the vulnerability class (denial of service), errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

Vendor	Product	Versions	Status	Source
Nodejs	Node	≥ 7.0 and < 7.≥ 18.0 and < 18.≥ 17.0 and < 17.≥ 16.0 and < 16.≥ 15.0 and < 15.≥ 14.0 and < 14.≥ 13.0 and < 13.≥ 12.0 and < 12. and 11 more ≥ 11.0 and < 11.≥ 10.0 and < 10.≥ 9.0 and < 9.≥ 8.0 and < 8.≥ 6.0 and < 6.≥ 5.0 and < 5.≥ 4.0 and < 4.*≥ 25.2.1 and ≤ 25.2.1≥ 24.12.0 and ≤ 24.12.0≥ 22.21.1 and ≤ 22.21.1≥ 20.19.6 and ≤ 20.19.6	Vulnerable	CVE Program (cve.org) e CISA ADP
Nodejs	Node.js	≥ 4.0.0 and < 20.20.0≥ 25.0.0 and < 25.3.0≥ 24.0.0 and < 24.13.0≥ 22.0.0 and < 22.22.0	Vulnerable	NIST National Vulnerability Database

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector

Network

Attack complexity

Low

Privileges required

None

User interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

None

Availability

High

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

Score	Version	Severity	Expl.	Impact	Scored by
7.5	CVSS 3.1	High	3.9	3.6	nvd@nist.gov via NIST National Vulnerability Database
5.9	CVSS 3.0	Medium	2.2	3.6	support@hackerone.com via NIST National Vulnerability Database
5.9	CVSS 3.0	Medium	—	—	hackerone via CVE Program (cve.org) e CISA ADP

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H (score shown at the top: nvd@nist.gov)

Scoring entities (NIST, CNA, ADP) score independently; each score is shown with its origin. For prioritization we use 7.5 (NVD (NIST)) as a conservative provisional reference — not a definitive official score.

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-400 · Uncontrolled Resource Consumption

Other CVEs with this weakness →

EPSS over time FIRST

Oct 13, 2026 → Oct 14, 2026 · 2 reading(s) · max 1.14%

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).
Track CPU/memory spikes and availability drops correlated with request patterns.

web/proxy/WAF logsnetwork IDS/IPSresource metrics

Timeline

What happened to this CVE, newest first.

2026
Affected products added · nodejs/node
Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
SSVC assessment updated
Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
Record published
Oct 13, 2026
CVSS changed · 7.5
Oct 13, 2026 · NIST National Vulnerability Database
Source status changed · → Analyzed
Oct 13, 2026 · NIST National Vulnerability Database
Record created in this database
Oct 13, 2026 · NIST National Vulnerability Database
CVE published
Jan 20, 2026 · hackerone

Source activity

Repeated readings are counted rather than listed.

1× Official description updated · Oct 13, 2026 – Oct 13, 2026

References

1 on the record

nodejs.org/en/blog/vulnerability/december-2025-security-releases
Release Notes, Vendor Advisory, NIST National Vulnerability Database

Elsewhere on this site

Nodejs
every CVE for this vendor

Denial of service
same class

CWE-400
other pages naming this weakness

Related CVEs (same products)

High CVE-2026-58043 Improper Access Control in Nodejs Node.js Jul 30, 2026
Medium CVE-2026-56850 Improper Authentication in Nodejs Node.js Jul 30, 2026
Medium CVE-2026-56847 A flaw in Node.js Permission Model enforcement allows `trace_events.createTracing().enabl… Jul 30, 2026
Low CVE-2026-48936 Improper Access Control in Nodejs Node.js Jun 25, 2026
Low CVE-2026-48935 Incorrect Default Permissions in Nodejs Node.js Jun 25, 2026
Medium CVE-2026-48618 A flaw in Node.js TLS hostname handling can cause Node.js unicode dot separator handling… Jun 25, 2026

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

No fixed version, patch or mitigation documented.
No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2026-21637 is "Uncontrolled Resource Consumption in Nodejs Node", rated High. It affects Node (Nodejs); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 7.5 describes technical severity. EPSS 1.14% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

Comments

Moderated technical discussion. Read the community guidelines.

No comments yet.