CVE-2026-48819Public exploitNetwork attack vector

Attacker-controlled property injection via unchecked prototype write

Published Jul 17, 2026 · Updated Jul 17, 2026

Prototype pollution in Hey API openapi-ts before 0.97.3 allows remote attackers to inject inherited properties into generated SDK parameters. buildClientParams strips slot prefixes from unknown keys and writes the remainder to a plain slot object, so $query___proto__ invokes the proto setter and replaces params.query's prototype. Exploitation requires an application to forward attacker-controlled input to a generated endpoint method; impact is limited to the returned slot and consumers that enumerate or trust inherited properties.

CVSS severity4.8
Medium
EPSS probability0.35%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Prototype pollution in Hey API openapi-ts before 0.97.3 allows remote attackers to inject inherited properties into generated SDK parameters. buildClientParams strips slot prefixes from unknown keys and writes the remainder to a plain slot object, so $query___proto__ invokes the proto setter and replaces params.query's prototype. Exploitation requires an application to forward attacker-controlled input to a generated endpoint method; impact is limited to the returned slot and consumers that enumerate or trust inherited properties.

The record

CVE
CVE-2026-48819
Published
Jul 17, 2026
Updated
Jul 17, 2026
Vendor
Hey API
Product
openapi-ts
Classifications
CWE-1321, CAPEC-1, CAPEC-180, CAPEC-77
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 17, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 17, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 0.97.3

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Hey API · openapi-tsversion=< 0.97.3

Published CVSS scores

4.8GitHubCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-1321Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')
CAPEC-1Accessing Functionality Not Properly Constrained by ACLs
CAPEC-180Exploiting Incorrectly Configured Access Control Security Levels
CAPEC-77Manipulating User-Controlled Variables

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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