CVE-2026-33396
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedOneUptime is an open-source monitoring and observability platform. Prior to version 10.0.35, a low-privileged authenticated user (ProjectMember) can achieve remote command execution on the Probe container/host by abusing Synthetic Monitor Playwright script execution. Synthetic monitor code is executed in VMRunner.runCodeInNodeVM with a live Playwright page object in context. The sandbox relies on a denylist of blocked properties/methods, but it is incomplete. Specifically, _browserType and launchServer are not blocked, so attacker code can traverse `page.context().browser()._browserType.launchServer(...)` and spawn arbitrary processes. Version 10.0.35 contains a patch.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceOneUptime versions before 10.0.35 allow a low-privileged authenticated user (ProjectMember) to achieve remote command execution through the Synthetic Monitor Playwright script execution feature. The sandbox uses a denylist to block dangerous properties/methods but is incomplete—specifically, `_browserType` and `launchServer` are not blocked. Attackers can traverse `page.context().browser()._browserType.launchServer(...)` to spawn arbitrary processes on the Probe container/host.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data< 10.0.35CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- Low
- User interaction
- None
- Scope
- Changed
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Identify installed OneUptime versionCheck your OneUptime installation's version number (typically found in the admin dashboard, about page, or package.json if self-hosted)Affected if The installed version is below 10.0.35 (e.g., 10.0.34, 10.0.30, etc.)
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Determine if Synthetic Monitor feature is activeLocate the Synthetic Monitor configuration in your OneUptime dashboard or config files and verify whether it is enabled for your organizationAffected if Synthetic Monitor feature is enabled and accessible to users
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Verify ProjectMember role access to script executionCheck user role permissions for the ProjectMember role, specifically whether they have access to the Synthetic Monitor Playwright script execution featureAffected if ProjectMember users can access or execute Synthetic Monitor scripts
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Inspect the denylist for blocked propertiesExamine the Synthetic Monitor sandbox configuration file where dangerous properties and methods are defined as blockedAffected if The denylist does not include `_browserType` and `launchServer` as blocked entries, or these entries are missing entirely from the configuration
Your environment is affected if you are running OneUptime below version 10.0.35 AND the Synthetic Monitor Playwright script execution feature is accessible to ProjectMember users, particularly if the denylist is missing protection against `_browserType` and `launchServer`.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
dbcve · scoped10.0.35
Upgrade to OneUptime version 10.0.35 or later which contains the complete denylist patch. As an interim measure, restrict or disable Synthetic Monitor script execution for ProjectMember users until the upgrade can be applied.
10.0.35
- 1. Identify the current installed version of OneUptime by checking the application's version endpoint or deployment configuration
- 2. If running a version lower than 10.0.35, plan for upgrade to version 10.0.35 or later
- 3. Backup the current OneUptime deployment, including database and configuration files
- 4. Upgrade OneUptime to version 10.0.35 by pulling the latest Docker images or updating the installation method used (e.g., Helm chart, Docker Compose, Kubernetes)
- 5. Verify the upgrade completed successfully by checking the application version
- 6. Test that Synthetic Monitor Playwright script execution still functions correctly for legitimate use cases
- 7. Confirm the sandbox now properly blocks access to `_browserType` and `launchServer` properties
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation3.0 h
- Implementation2.0 h
- Testing6.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-33396 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-33396 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
- No spam, self-promotion, credentials, or personal data