---
title: "CVE-2026-30956: OneUptime has authorization bypass via client‑controlled is-multi-tenant-query header that leads to cross‑tenant data exposure and account takeover"
url: https://erroneo.us/security/cve/CVE-2026-30956/
description: "CVE-2026-30956 (@oneuptime/common (npm)): OneUptime is a solution for monitoring and managing online services. Prior to 10.0.21, a low‑privileged user can…"
type: vulnerability-record
section: "Security Digest"
date_published: 2026-03-10
date_modified: 2026-03-10
publisher: erroneo.us
author: erroneo.us Security Desk
cve: "CVE-2026-30956"
kev: false
cvss: 10
epss: 0.00503
license: All rights reserved. Quote with attribution and a link.
---

# CVE-2026-30956: OneUptime has authorization bypass via client‑controlled is-multi-tenant-query header that leads to cross‑tenant data exposure and account takeover

**Signal:** Critical, preconditions apply. Severe if exploited, but exploitation needs conditions that may not apply to you. (Computed from CISA KEV, EPSS and CVSS; not an editorial verdict.)

## Should you act?

- No confirmed exploitation. It is not in CISA’s KEV catalog and CISA’s SSVC assessment records no known exploitation. That can change quickly after a public write-up; re-check if you are affected.
- EPSS 0.5% , percentile 42: FIRST’s model estimates a 0.5% chance of exploitation activity in the next 30 days, higher than 42% of all scored CVEs (low). 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) < 10.0.21, fixed in 10.0.21 . Check your lockfile, including transitive dependencies.

## What it is

OneUptime is a solution for monitoring and managing online services. Prior to 10.0.21, a low‑privileged user can bypass authorization and tenant isolation in OneUptime v10.0.20 and earlier by sending a forged is-multi-tenant-query header together with a controlled projectid header. Because the server trusts this client-supplied header, internal permission checks in BasePermission are skipped and tenant scoping is disabled. This allows attackers to access project data belonging to other tenants, read sensitive User fields via nested relations, leak plaintext resetPasswordToken, and reset the victim’s password and fully take over the account. This results in cross‑tenant data exposure and full account takeover. This vulnerability is fixed in 10.0.21.

## Affected packages

- npm `@oneuptime/common` < 10.0.21 → fixed: 10.0.21

## Affected products (CVE record)

- OneUptime oneuptime: < 10.0.21

## Severity

- GitHub_M CVSS 3.1: 10 `CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H`
- GitHub CVSS 3.1: 9.9 `CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H`

## Exploitation

- CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
- CISA SSVC assessment: exploitation none , automatable no , technical impact total .
- FIRST EPSS (model of 2026-10-21): 0.50% probability of exploitation activity in the next 30 days; percentile 42.

## Sources

- [GitHub Advisory GHSA-r5v6-2599-9g3m](https://github.com/advisories/GHSA-r5v6-2599-9g3m)
- [CVE.org record CVE-2026-30956](https://www.cve.org/CVERecord?id=CVE-2026-30956)
- [NVD entry CVE-2026-30956](https://nvd.nist.gov/vuln/detail/CVE-2026-30956)
- [github.com](https://github.com/OneUptime/oneuptime/security/advisories/GHSA-r5v6-2599-9g3m)
- [github.com](https://github.com/OneUptime/oneuptime/releases/tag/10.0.21)

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Source page: https://erroneo.us/security/cve/CVE-2026-30956/ · Security Digest: https://erroneo.us/security/ · More: https://erroneo.us/llms.txt