CVE-2026-33396
Published: 26 March 2026
Description
OneUptime 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…
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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.
Mitigating Controls (NIST 800-53 r5)AI
Enforces software-based separation and policy in the VMRunner sandbox, directly addressing the incomplete denylist that permitted traversal via page.context().browser()._browserType.launchServer() to spawn arbitrary processes.
Provides process isolation for the Synthetic Monitor Playwright script execution environment, preventing sandbox escape and remote command execution on the Probe container or host.
Controls mobile code execution such as user-supplied Playwright scripts, mitigating risks from incomplete sandboxing that allows low-privileged users to achieve RCE.
Security SummaryAI
CVE-2026-33396 is a high-severity vulnerability in OneUptime, an open-source monitoring and observability platform, affecting versions prior to 10.0.35. It stems from an incomplete sandbox in the Synthetic Monitor Playwright script execution feature, where user-supplied code runs in VMRunner.runCodeInNodeVM alongside a live Playwright page object. The sandbox uses a denylist of blocked properties and methods, but fails to block _browserType and launchServer, enabling traversal via page.context().browser()._browserType.launchServer(...) to spawn arbitrary processes and achieve remote command execution (RCE) on the Probe container or host. The issue is classified under CWE-78 (OS Command Injection), CWE-184 (Incomplete List of Disallowed Inputs), and CWE-693 (Protection Mechanism Failure), with a CVSS v3.1 base score of 9.9 (AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H).
A low-privileged authenticated user with ProjectMember role can exploit this vulnerability remotely over the network with low complexity and no user interaction required. By crafting malicious Synthetic Monitor scripts, the attacker bypasses the sandbox to execute arbitrary commands on the affected Probe container or host, potentially leading to full compromise including high confidentiality, integrity, and availability impacts due to the high scope change.
The GitHub security advisory (GHSA-cqpg-phpp-9jjg) and associated patch commit detail mitigation via version 10.0.35, which addresses the incomplete denylist in the Playwright sandbox to prevent the traversal and command execution. Security practitioners should upgrade to 10.0.35 or later and review access to ProjectMember roles in Synthetic Monitor configurations.
Details
- CWE(s)
Affected Products
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
The vulnerability enables low-privileged authenticated users to remotely exploit a public-facing application via crafted scripts in an incomplete sandbox, achieving RCE on the Probe container/host (T1190). This directly facilitates privilege escalation from ProjectMember role to full compromise (T1068).