CVE-2026-27574: OneUptime:: node:vm sandbox escape in probe allows any project member to achieve RCE

Should you act?

Critical, preconditions apply

Severe if exploited, but exploitation needs conditions that may not apply to you. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.

• Not in CISA KEV, but CISA’s SSVC assessment records a public proof-of-concept, so attack code exists.
• EPSS 0.7%, percentile 52: FIRST’s model estimates a 0.7% chance of exploitation activity in the next 30 days, higher than 52% of all scored CVEs (moderate). 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) < 10.0.0, fixed in 10.0.0. Check your lockfile, including transitive dependencies.

What it is

OneUptime is a solution for monitoring and managing online services. In versions 9.5.13 and below, custom JavaScript monitor feature uses Node.js's node:vm module (explicitly documented as not a security mechanism) to execute user-supplied code, allowing trivial sandbox escape via a well-known one-liner that grants full access to the underlying process. Because the probe runs with host networking and holds all cluster credentials (ONEUPTIMESECRET, DATABASEPASSWORD, REDISPASSWORD, CLICKHOUSEPASSWORD) in its environment variables, and monitor creation is available to the lowest role (ProjectMember) with open registration enabled by default, any anonymous user can achieve full cluster compromise in about 30 seconds. This issue has been fixed in version 10.0.5.

From the GitHub advisory

Summary

OneUptime lets project members write custom JavaScript that runs inside monitors. The problem is it executes that code using Node.js's built-in vm module, which Node.js itself documents as "not a security mechanism — do not use it to run untrusted code." The classic one-liner escape gives full access to the underlying process, and since the probe runs with host networking and holds all cluster credentials in its environment, this turns into a full cluster compromise for anyone who can register an account.

Details

The vulnerable code is in Common/Server/Utils/VM/VMRunner.ts at line 55:

The JavaScript that reaches this call comes straight from the monitor's customCode field, which is only validated as Zod.string().optional() in Common/Types/Monitor/MonitorStep.ts:531. No AST analysis, no keyword filtering, nothing — just a string that goes directly into vm.runInContext().

Weakness type: CWE-94.

Product: @oneuptime/common (npm) · Assigned by: GitHub_M · Published: 2026-02-21

Affected and fixed versions

Severity scores

• Attack vector: network (remotely reachable)
• Attack complexity: low
• Privileges required: low (any account)
• User interaction: none
• Scope: changed (can affect other components)

CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.

Exploitation and urgency

• 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): 0.69% probability of exploitation activity in the next 30 days; percentile 52.

Timeline

• 2026-02-21 — CVE record published by GitHub_M
• 2026-02-24 — CVE record last updated
• 2026-02-24 — GitHub-reviewed advisory GHSA-v264-xqh4-9xmm published (critical)

Sources and references

Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.

Vulnerability records

1. GitHub Advisory GHSA-v264-xqh4-9xmm github.com
2. CVE.org record CVE-2026-27574 cve.org
3. NVD entry CVE-2026-27574 nvd.nist.gov

Other references from the CVE record and advisory

1. github.com github.com
2. github.com github.com

Critical npm advisories · Today’s Security Digest