What is CVE-2026-58172?

CVE-2026-58172 is a critical-severity vulnerability in Threemammals Ocelot, classified under Authentication Bypass Using an Alternate Path or Channel. CVSS score: 9.1/10. Published 2026-06-30.

How severe is CVE-2026-58172?

Critical severity. CVSS v3 base score is 9.1 out of 10.

Vulnerability in Threemammals Ocelot

CVE-2026-58172

Ocelot through 24.1.0, fixed in commit f156fd4, contains a security control bypass vulnerability that allows denied clients to circumvent IP-based access restrictions by sending WebSocket upgrade requests. The WebSocket upgrade pipeline branch configured via MapWhen in OcelotPipelineExtensions.cs omits SecurityMiddleware, causing requests from blocked IP addresses to be proxied to downstream services without enforcement of the configured allow/block list.

EPSS: 0.004 (33.8th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 9.1 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N.

Affected products

Threemammals Ocelot — versions 0, f156fd4017ca25025fffdad8ec56c1d657dfb402

Weakness classification (CWE)

CWE-288 — Authentication Bypass Using an Alternate Path or Channel

References

disclosure@vulncheck.com (technical-description, exploit)
disclosure@vulncheck.com (issue-tracking)
disclosure@vulncheck.com (patch)
disclosure@vulncheck.com (third-party-advisory)

Frequently asked questions

What is CVE-2026-58172?: CVE-2026-58172 is a critical-severity vulnerability in Threemammals Ocelot, classified under Authentication Bypass Using an Alternate Path or Channel. CVSS score: 9.1/10. Published 2026-06-30.
How severe is CVE-2026-58172?: Critical severity. CVSS v3 base score is 9.1 out of 10.