CVE-2026-119552 (CVSS 4.8)

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.

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CVSS v3.1 Score

4.8

MEDIUM

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N

EPSS — Exploit Prediction

0.0023

Probability of exploitation

0.14%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-367 CWE-367

References

Other 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-admin-creation-via-setup-handler

Frequently Asked Questions

What is CVE-2026-119552? +

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. It has a CVSS v3.1 base score of 4.8 (MEDIUM).

How severe is CVE-2026-119552? +

CVE-2026-119552 has a CVSS v3.1 score of 4.8 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0023, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-119552? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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