CVE-2026-30921 — @oneuptime/common
CRITICALCVE-2026-30921 is a critical-severity (CVSS 9.9) CWE-749 vulnerability in @oneuptime/common. A fix is available for @oneuptime/common — see the affected versions and patch details below.
OneUptime Synthetic Monitor RCE via exposed Playwright browser object
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
- A successful exploit gives an attacker total control of the affected component, not partial access.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-30921.
EPSS Exploitation Probability
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.
How urgent is this, really
CVE-2026-30921 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 378,567 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.
@oneuptime/commonnpmDescription
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:
- https://github.com/OneUptime/oneuptime/blob/8e90f451426b160718bdd1796b68c5ec15318101/Common/Models/DatabaseModels/Monitor.ts#L45-L78
- https://github.com/OneUptime/oneuptime/blob/8e90f451426b160718bdd1796b68c5ec15318101/Common/Models/DatabaseModels/MonitorTest.ts#L27-L60
The dashboard exposes a Playwright code editor for Synthetic Monitors and allows the user to queue a test run:
- https://github.com/OneUptime/oneuptime/blob/8e90f451426b160718bdd1796b68c5ec15318101/App/FeatureSet/Dashboard/src/Components/Form/Monitor/MonitorStep.tsx#L861-L918
- https://github.com/OneUptime/oneuptime/blob/8e90f451426b160718bdd1796b68c5ec15318101/App/FeatureSet/Dashboard/src/Components/Form/Monitor/MonitorTest.tsx#L66-L84
The probe worker polls queued monitor tests and executes them:
For MonitorType.SyntheticMonitor, the user-controlled customCode is passed into SyntheticMonitor.execute(...):
SyntheticMonitor.execute(...) then runs that code through VMRunner.runCodeInNodeVM(...) and injects the live Playwright browser and page objects into the VM context:
VMRunner.runCodeInNodeVM(...) creates a Node vm context and exposes host objects into it, including the additional context objects:
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:
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 Monitorand choose a probe.
Expected result:
- the monitor execution succeeded and in the
Show More Detailsthe 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
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | @oneuptime/common | all versions | 10.0.20npm install @oneuptime/common@10.0.20 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for @oneuptime/common, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update @oneuptime/common to 10.0.20 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-30921 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 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2026-30921 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2026-30921. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-30921 in your dependencies?
O3 Security finds CVE-2026-30921 across npm dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.