---
title: "CVE-2026-49252: deepstream is vulnerable to prototype pollution"
url: https://erroneo.us/security/cve/CVE-2026-49252/
description: "CVE-2026-49252 (@deepstream/server (npm)): deepstream is a server that allows clients and backend services to sync data, send messages and make rpcs at…"
type: vulnerability-record
section: "Security Digest"
date_published: 2026-06-18
date_modified: 2026-06-26
publisher: erroneo.us
author: erroneo.us Security Desk
cve: "CVE-2026-49252"
kev: false
cvss: 9.9
epss: 0.0047
license: All rights reserved. Quote with attribution and a link.
---

# CVE-2026-49252: deepstream is vulnerable to prototype pollution

**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 0.5% , percentile 40: FIRST’s model estimates a 0.5% chance of exploitation activity in the next 30 days, higher than 40% of all scored CVEs (low). EPSS is a probability, not a verdict.
- Needs an account (low (any account)). Exposure depends on who can log in.
- Only applies if your dependency tree includes @deepstream/server (npm) < 10.0.5, fixed in 10.0.5 . Check your lockfile, including transitive dependencies.

## What it is

deepstream is a server that allows clients and backend services to sync data, send messages and make rpcs at scale. Versions prior to 10.0.5 are vulnerable to Prototype Pollution. Exploitation can lead to potential privilege escalation from any authenticated user with write permission to any record. This issue has been fixed in version 10.0.5.

## Affected packages

- npm `@deepstream/server` < 10.0.5 → fixed: 10.0.5

## Affected products (CVE record)

- deepstreamIO deepstream.io: < 10.0.5

## Severity

- GitHub_M CVSS 3.1: 9.9 `CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:L`
- GitHub CVSS 3.1: 9.9 `CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:L`

## Exploitation

- CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
- CISA SSVC assessment: exploitation none , automatable no , technical impact partial .
- FIRST EPSS (model of 2026-10-21): 0.47% probability of exploitation activity in the next 30 days; percentile 40.

## Sources

- [GitHub Advisory GHSA-9v98-6g37-x9g6](https://github.com/advisories/GHSA-9v98-6g37-x9g6)
- [CVE.org record CVE-2026-49252](https://www.cve.org/CVERecord?id=CVE-2026-49252)
- [NVD entry CVE-2026-49252](https://nvd.nist.gov/vuln/detail/CVE-2026-49252)
- [github.com](https://github.com/deepstreamIO/deepstream.io/security/advisories/GHSA-9v98-6g37-x9g6)
- [github.com](https://github.com/deepstreamIO/deepstream.io/commit/54b8e2958a98df444b5b5d9a66e22872afd84e44)

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Source page: https://erroneo.us/security/cve/CVE-2026-49252/ · Security Digest: https://erroneo.us/security/ · More: https://erroneo.us/llms.txt