CVE-2026-119552

Description

Uptime Kuma through 2.5.8 contains a race condition in the Socket.IO first-run setup handler that allows unauthenticated attackers to create an additional administrator account. Attackers can send concurrent setup requests during the bcrypt hashing window to bypass the empty user table check, then modify monitors, API keys, and enable disableAuth.

Metrics

CVSS 3.1

4.8 (MEDIUM) Score source: CNA CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N

CVSS 4.0

6.3 (MEDIUM) Score source: CNA CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

EPSS — exploit probability

0% (percentile: 14) as of 1 November 2026

CWE

CWE-367

References

• https://abraxaslabs.tech/research/uptime-kuma-setup-toctou
• https://github.com/louislam/uptime-kuma
• https://github.com/louislam/uptime-kuma/blob/2.5.8/server/server.js#L705-L722
• https://www.vulncheck.com/advisories/uptime-kuma-through-2.5.8-race-condition-a…