---
title: "CVE-2026-30921: OneUptime: Synthetic Monitor RCE via exposed Playwright browser object"
url: https://erroneo.us/security/cve/CVE-2026-30921/
description: "CVE-2026-30921 (@oneuptime/common (npm)): OneUptime is a solution for monitoring and managing online services. Prior to 10.0.20, OneUptime Synthetic…"
type: vulnerability-record
section: "Security Digest"
date_published: 2026-03-09
date_modified: 2026-03-10
publisher: erroneo.us
author: erroneo.us Security Desk
cve: "CVE-2026-30921"
kev: false
cvss: 10
epss: 0.00538
license: All rights reserved. Quote with attribution and a link.
---

# CVE-2026-30921: OneUptime: Synthetic Monitor RCE via exposed Playwright browser object

**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?

- Not in CISA KEV , but CISA’s SSVC assessment records a public proof-of-concept, so attack code exists.
- EPSS 0.5% , percentile 44: FIRST’s model estimates a 0.5% chance of exploitation activity in the next 30 days, higher than 44% 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 @oneuptime/common (npm) < 10.0.20, fixed in 10.0.20 . Check your lockfile, including transitive dependencies.

## What it is

OneUptime is a solution for monitoring and managing online services. Prior to 10.0.20, OneUptime Synthetic Monitors allow low-privileged project users to submit custom Playwright code that is executed on the oneuptime-probe service. In the current implementation, this untrusted code is run inside Node's vm and is given live host Playwright objects such as browser and page. This creates a distinct server-side RCE primitive: the attacker does not need the classic this.constructor.constructor(...) sandbox escape. Instead, the attacker can directly use the injected Playwright browser object to reach browser.browserType().launch(...) and spawn an arbitrary executable on the probe host/container. This vulnerability is fixed in 10.0.20.

## Affected packages

- npm `@oneuptime/common` < 10.0.20 → fixed: 10.0.20

## Affected products (CVE record)

- OneUptime oneuptime: < 10.0.20

## Severity

- GitHub_M CVSS 3.1: 10 `CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H`
- GitHub CVSS 3.1: 9.9 `CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H`

## Exploitation

- CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
- CISA SSVC assessment: exploitation poc , automatable no , technical impact total .
- FIRST EPSS (model of 2026-10-21): 0.54% probability of exploitation activity in the next 30 days; percentile 44.

## Sources

- [GitHub Advisory GHSA-4j36-39gm-8vq8](https://github.com/advisories/GHSA-4j36-39gm-8vq8)
- [CVE.org record CVE-2026-30921](https://www.cve.org/CVERecord?id=CVE-2026-30921)
- [NVD entry CVE-2026-30921](https://nvd.nist.gov/vuln/detail/CVE-2026-30921)
- [github.com](https://github.com/OneUptime/oneuptime/security/advisories/GHSA-4j36-39gm-8vq8)
- [github.com](https://github.com/OneUptime/oneuptime/blob/8e90f451426b160718bdd1796b68c5ec15318101/App/FeatureSet/Dashboard/src/Components/Form/Monitor/MonitorStep.tsx#L861-L918)
- [github.com](https://github.com/OneUptime/oneuptime/blob/8e90f451426b160718bdd1796b68c5ec15318101/App/FeatureSet/Dashboard/src/Components/Form/Monitor/MonitorTest.tsx#L66-L84)
- [github.com](https://github.com/OneUptime/oneuptime/blob/8e90f451426b160718bdd1796b68c5ec15318101/Common/Models/DatabaseModels/Monitor.ts#L45-L78)
- [github.com](https://github.com/OneUptime/oneuptime/blob/8e90f451426b160718bdd1796b68c5ec15318101/Common/Models/DatabaseModels/MonitorTest.ts#L27-L60)
- [github.com](https://github.com/OneUptime/oneuptime/blob/8e90f451426b160718bdd1796b68c5ec15318101/Common/Server/Utils/VM/VMRunner.ts#L323-L405)
- [github.com](https://github.com/OneUptime/oneuptime/blob/8e90f451426b160718bdd1796b68c5ec15318101/Probe/Jobs/Monitor/FetchList.ts#L110-L121)
- [github.com](https://github.com/OneUptime/oneuptime/blob/8e90f451426b160718bdd1796b68c5ec15318101/Probe/Jobs/Monitor/FetchMonitorTest.ts#L55-L85)
- [github.com](https://github.com/OneUptime/oneuptime/blob/8e90f451426b160718bdd1796b68c5ec15318101/Probe/Utils/Monitors/Monitor.ts#L323-L338)
- [github.com](https://github.com/OneUptime/oneuptime/blob/8e90f451426b160718bdd1796b68c5ec15318101/Probe/Utils/Monitors/MonitorTypes/SyntheticMonitor.ts#L156-L168)

---
Source page: https://erroneo.us/security/cve/CVE-2026-30921/ · Security Digest: https://erroneo.us/security/ · More: https://erroneo.us/llms.txt