---
title: "CVE-2026-25047: deepHas vulnerable to Prototype Pollution via constructor.prototype"
url: https://erroneo.us/security/cve/CVE-2026-25047/
description: "CVE-2026-25047 (deephas (npm)): deepHas provides a test for the existence of a nested object key and optionally returns that key. A prototype pollution…"
type: vulnerability-record
section: "Security Digest"
date_published: 2026-01-29
date_modified: 2026-02-27
publisher: erroneo.us
author: erroneo.us Security Desk
cve: "CVE-2026-25047"
kev: false
cvss: 9.4
epss: 0.00808
license: All rights reserved. Quote with attribution and a link.
---

# CVE-2026-25047: deepHas vulnerable to Prototype Pollution via constructor.prototype

**Signal:** Critical, preconditions apply. Severe if exploited, but exploitation needs conditions that may not apply to you. (Computed from CISA KEV, EPSS and CVSS; not an editorial verdict.)

## Should you act?

- No confirmed exploitation. It is not in CISA’s KEV catalog and CISA’s SSVC assessment records no known exploitation. That can change quickly after a public write-up; re-check if you are affected.
- EPSS 0.8% , percentile 56: FIRST’s model estimates a 0.8% chance of exploitation activity in the next 30 days, higher than 56% of all scored CVEs (moderate). EPSS is a probability, not a verdict.
- Needs local access needed. Lower urgency for most teams unless an attacker could already run code on the machine.
- Only applies if your dependency tree includes deephas (npm) < 1.0.8, fixed in 1.0.8 . Check your lockfile, including transitive dependencies.

## What it is

deepHas provides a test for the existence of a nested object key and optionally returns that key. A prototype pollution vulnerability exists in version 1.0.7 of the deephas npm package that allows an attacker to modify global object behavior. This issue was fixed in version 1.0.8.

## Affected packages

- npm `deephas` < 1.0.8 → fixed: 1.0.8

## Affected products (CVE record)

- sharpred deepHas: < 1.0.7

## Severity

- GitHub_M CVSS 4.0: 9.4 `CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H`
- GitHub CVSS 4.0: 9.4 `CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H`

## Exploitation

- CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
- CISA SSVC assessment: exploitation none , automatable no , technical impact total .
- FIRST EPSS (model of 2026-10-21): 0.81% probability of exploitation activity in the next 30 days; percentile 56.

## Sources

- [GitHub Advisory GHSA-2733-6c58-pf27](https://github.com/advisories/GHSA-2733-6c58-pf27)
- [CVE.org record CVE-2026-25047](https://www.cve.org/CVERecord?id=CVE-2026-25047)
- [NVD entry CVE-2026-25047](https://nvd.nist.gov/vuln/detail/CVE-2026-25047)
- [github.com](https://github.com/sharpred/deepHas/security/advisories/GHSA-2733-6c58-pf27)
- [github.com](https://github.com/sharpred/deepHas/commit/8097fafd3776c613d8066546653e0d2c7b5fc465)

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Source page: https://erroneo.us/security/cve/CVE-2026-25047/ · Security Digest: https://erroneo.us/security/ · More: https://erroneo.us/llms.txt