CVE-2026-48819

MEDIUMPre-NVD 4.84.8—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 4.8 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.4%, top 72% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, secondary
Elevated
4.8
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS: 0%CVSS: 4.8Exploit: NoneExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

Hey API is an ecosystem for turning API specifications into production-ready code. Prior to 0.97.3, dist/clients/core/params.ts ships a runtime template copied into generated SDKs as params.gen.ts, and buildClientParams writes unknown slot-prefixed keys such as $body_, $headers_, $path_, and $query_ directly to the corresponding slot, allowing $query___proto__ alongside a legitimate q field to set params.query through params["query"]["__proto__"] = value, call Object.setPrototypeOf(params.query, value), and expose inherited attacker-controlled keys during for..in iteration. This issue is fixed in version 0.97.3.

CVSS v3
4.8
EG Score
4.8(medium)
EG Risk
38(Track)
EG Risk 38/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity48% × 45%
Exploitation40% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS
27.7%
KEV
Not listed

Published

July 1, 2026

Last Modified

July 23, 2026

Advisory Details (3)

Auto-updated Jul 17, 2026
🔬 Proof of concept available. Patch available. Sources: github, github_commit.
github_commit Patch Available

commit da321a1529eb (hey-api/hey-api)

Patch available: hey-api/hey-api 2026-06-22 (contains commit da321a1529eb)

https://github.com/hey-api/hey-api/commit/da321a1529eb3c90d2109da870f514b915a60169
github_commit Patch Available

commit 023909137a15 (hey-api/hey-api)

Patch available: hey-api/hey-api 2026-06-22 (contains commit 023909137a15)

https://github.com/hey-api/hey-api/commit/023909137a15eff9c0263d3bcd116140076b214f
github Patch Available🟡 PoC Available

`buildClientParams` template: prototype chain substitution via unknown `$<slot>___proto__` key · Advisory · hey-api/hey-api · GitHub

https://github.com/hey-api/hey-api/security/advisories/GHSA-hhx9-57xq-r5rw

Vendor Advisories for CVE-2026-48819(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Affected Packages

(1 across 1 ecosystem)
npm(1)
PackageVulnerable rangeFixed inDependents
@hey-api/openapi-ts—0.97.3—

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 9× in last 7d / 10× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-07-23 14:18 UTCEPSS rescore
  2. 2026-07-23 03:18 UTCEG score recompute
  3. 2026-07-22 14:08 UTCEPSS rescore
  4. 2026-07-21 15:25 UTCEPSS rescore
  5. 2026-07-20 17:08 UTCEPSS rescore
  6. 2026-07-19 14:31 UTCEPSS rescore
  7. 2026-07-19 14:31 UTCEPSS rescore
  8. 2026-07-19 03:52 UTCEG score recompute
  9. 2026-07-19 02:29 UTCEPSS rescore
  10. 2026-07-01 21:02 UTCEG score recompute

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-48819?
CVE-2026-48819 is a medium vulnerability published on July 1, 2026. Hey API is an ecosystem for turning API specifications into production-ready code. Prior to 0.97.3, dist/clients/core/params.ts ships a runtime template copied into generated SDKs as params.gen.ts, and buildClientParams writes unknown slot-prefixed keys such as $body, $headers, $path, and $query…
When was CVE-2026-48819 disclosed?
CVE-2026-48819 was first published in the National Vulnerability Database on July 1, 2026, with the most recent update on July 23, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-48819 actively exploited?
CVE-2026-48819 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 27.7% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-48819?
CVE-2026-48819 has a CVSS v3 base score of 4.8 (NVD).
How do I remediate CVE-2026-48819?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-48819, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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