How severe is GHSA-4j36-39gm-8vq8?

GHSA-4j36-39gm-8vq8 has a CVSS score of 9.9/10, rated CRITICAL. Immediate patching is strongly recommended.

Which packages are affected by GHSA-4j36-39gm-8vq8?

GHSA-4j36-39gm-8vq8 affects the following packages: @oneuptime/common (npm). Ecosystems affected: npm.

How do I fix GHSA-4j36-39gm-8vq8?

Update @oneuptime/common to 10.0.20 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-4j36-39gm-8vq8 is resolved across your whole dependency graph.

How do I detect GHSA-4j36-39gm-8vq8 in my npm dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for @oneuptime/common. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.

How do I mitigate GHSA-4j36-39gm-8vq8 if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

How does O3 Security protect against GHSA-4j36-39gm-8vq8?

O3 pinpoints whether GHSA-4j36-39gm-8vq8 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Is GHSA-4j36-39gm-8vq8 actively exploited in the wild?

No public exploit code has been indexed for GHSA-4j36-39gm-8vq8 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for GHSA-4j36-39gm-8vq8?

GHSA-4j36-39gm-8vq8 has an EPSS (Exploit Prediction Scoring System) score of 0.4%, placing it in the 35th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is GHSA-4j36-39gm-8vq8?

GHSA-4j36-39gm-8vq8 is classified as CWE-749 (CWE-749). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was GHSA-4j36-39gm-8vq8 published, and has it been updated?

GHSA-4j36-39gm-8vq8 was published on March 7, 2026 and was last updated on March 10, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

GHSA-4j36-39gm-8vq8: @oneuptime/common Remote Code Execution (C…

EPSS Exploitation Probability

via FIRST.org ↗

0.4%probability of exploitation in next 30 days

Lower Risk35th percentile+0.42%

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

Blast Radius

1 pkg affected

📦@oneuptime/common

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects npm packages — download data is not available via public APIs for these ecosystems.

Description

Summary

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 appears to be a separate issue from the previously published node:vm(GHSA-h343-gg57-2q67) breakout advisory because the root cause here is exposure of a dangerous host capability object to untrusted code, not prototype-chain access to process.

Details

A normal project member can create or edit monitors and monitor tests:

The dashboard exposes a Playwright code editor for Synthetic Monitors and allows the user to queue a test run:

The probe worker polls queued monitor tests and executes them:

https://github.com/OneUptime/oneuptime/blob/8e90f451426b160718bdd1796b68c5ec15318101/Probe/Jobs/Monitor/FetchMonitorTest.ts#L55-L85

For MonitorType.SyntheticMonitor, the user-controlled customCode is passed into SyntheticMonitor.execute(...):

https://github.com/OneUptime/oneuptime/blob/8e90f451426b160718bdd1796b68c5ec15318101/Probe/Utils/Monitors/Monitor.ts#L323-L338

SyntheticMonitor.execute(...) then runs that code through VMRunner.runCodeInNodeVM(...) and injects the live Playwright browser and page objects into the VM context:

https://github.com/OneUptime/oneuptime/blob/8e90f451426b160718bdd1796b68c5ec15318101/Probe/Utils/Monitors/MonitorTypes/SyntheticMonitor.ts#L156-L168

VMRunner.runCodeInNodeVM(...) creates a Node vm context and exposes host objects into it, including the additional context objects:

https://github.com/OneUptime/oneuptime/blob/8e90f451426b160718bdd1796b68c5ec15318101/Common/Server/Utils/VM/VMRunner.ts#L323-L405

The proxy wrapper blocks only a small set of property names and still forwards normal method calls with the real host this binding. Because of that, untrusted monitor code can still use legitimate Playwright methods on the injected browser object.

That is enough for code execution because Playwright's Browser exposes browserType(), and BrowserType.launch() accepts attacker-controlled process launch options such as executablePath, args, and ignoreDefaultArgs. An attacker can therefore cause the probe to spawn an arbitrary executable. Even if Playwright later errors because the spawned process is not a real browser, the command has already executed.

This same execution path is also used for normal scheduled monitors, not only one-shot monitor tests:

https://github.com/OneUptime/oneuptime/blob/8e90f451426b160718bdd1796b68c5ec15318101/Probe/Jobs/Monitor/FetchList.ts#L110-L121

As a result, the issue can be abused either as a one-shot RCE via Test Monitor or as a persistent scheduled RCE by saving a malicious Synthetic Monitor.

PoC

Log in as any user with normal project membership.
Go to Monitors -> Create New Monitor.
Select Synthetic Monitor.
In Playwright Code, paste the following script:

 const HostFunction =
    Object.getOwnPropertyDescriptor(console, "log").value.constructor;

  return {
    data: {
      node: HostFunction('return process.version')(),
      cwd: HostFunction('return process.cwd()')(),
      id: HostFunction(
        'return process.getBuiltinModule("child_process").execSync("id").toString()'
      )(),
    },
  };

Select any one browser type, for example Chromium.
Select any one screen type, for example Desktop.
Set retry count to 0.
Click Test Monitor and choose a probe.

Expected result:

the monitor execution succeeded and in the Show More Details the command output is shown. <img width="899" height="249" alt="image" src="https://github.com/user-attachments/assets/98ebd26f-431b-438e-9459-7deeebf97b18" />

Impact

This is a server-side Remote Code Execution issue affecting the probe component.

Who is impacted:

any OneUptime deployment where an attacker can obtain ordinary project membership
environments where the probe has access to internal services, secrets, Kubernetes metadata, database credentials, proxy credentials, or other cluster-local trust relationships

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
📦npm	`@oneuptime/common`	all versions	10.0.20

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for @oneuptime/common. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update @oneuptime/common to 10.0.20 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-4j36-39gm-8vq8 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-4j36-39gm-8vq8 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Tailored to GHSA-4j36-39gm-8vq8. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

Summary 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 exe

O3 Security · Impact-Aware SCA

Is GHSA-4j36-39gm-8vq8 in your dependencies?

O3 detects GHSA-4j36-39gm-8vq8 across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.

Scan my dependencies How O3 SCA works

GHSA-4j36-39gm-8vq8