CVE-2026-21710

HIGHPre-NVD 7.57.5Elevated

Also known asEUVD-2026-17170 (ENISA EUVD) · GHSA-xv6w-gxj8-v943 (GitHub Security Advisories)Source: ENISA EUVD

7.5EG

EchelonGraph verdictPlan a fixRemediate within your standard update timelines at low or medium mission impact and sooner than that at high (the SSVC decision on this page).

High severity, but no confirmed exploitation yet

CISA-KEV: Not listedEPSS PROB: 25%CVSS: 7.5Exploit: No code on recordExposed services: Not assessed

A fix is available — apply it.

A flaw in Node.js HTTP request handling causes an uncaught TypeError when a request is received with a header named __proto__ and the application accesses req.headersDistinct. When this occurs, dest["__proto__"] resolves to Object.prototype rather than undefined, causing .push() to be called on a non-array. This exception is thrown synchronously inside a property getter and cannot be intercepted by error event listeners, meaning it cannot be handled without wrapping every req.headersDistinct access in a try/catch. * This vulnerability affects all Node.js HTTP servers on 20.x, 22.x, 24.x, and v25.x

CVSS v3: 7.5
EG Score: 7.5HIGHmedium confidence
EG Risk: 65
EPSS PROB: 25%
EPSS %ILE: 97th
KEV: Not listed

What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)

The EG score (7.5): severity, escalated by confirmed exploitation. This CVE's 7.5 is its impact severity (EG Severity), not escalated.

EG Severity: 7.5 HIGHCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
EG Likelihood: 25% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-11-12). FIRST's exploitation probability, not an EchelonGraph model.
Confirmed exploitation: None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
EG Priority: SSVC Track at medium mission impactTrack at low or medium mission impact; Attend at high (mission-essential systems).CISA BOD 26-04: 14 days if the affected system is publicly exposed; 60 days if it is not.Each input and its source, and whom BOD 26-04 binds: the SSVC and BOD 26-04 blocks below.

SSVC (CISA's decision table, applied by EchelonGraph)Track at low or medium mission impact; Attend at high (mission-essential systems).

A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.

Exploitation none (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table

BOD 26-04 (CISA's remediation timeline, Table 1)14 days if the affected system is publicly exposed; 60 days if it is not.

The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable yes (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it

Published

March 30, 2026

Last Modified

August 19, 2026