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

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.

• 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.

From the GitHub advisory

Summary A low‑privileged user can bypass authorization and tenant isolation in OneUptime v10.0.20 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:

1. Access project data belonging to other tenants 2. Read sensitive User fields via nested relations 3. Leak plaintext resetPasswordToken 4. Reset the victim’s password and fully take over the account

This results in cross‑tenant data exposure and full account takeover.

Weakness type: CWE-285, CWE-862.

Product: @oneuptime/common (npm) · Assigned by: GitHub_M · Published: 2026-03-10

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 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.

Timeline

• 2026-03-10 — CVE record last updated
• 2026-03-10 — CVE record published by GitHub_M
• 2026-03-10 — GitHub-reviewed advisory GHSA-r5v6-2599-9g3m 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-r5v6-2599-9g3m github.com
2. CVE.org record CVE-2026-30956 cve.org
3. NVD entry CVE-2026-30956 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