CVE-2026-58172

CRITICAL 9.1

Ocelot - IP Allow/Block List Bypass for WebSocket Upgrade Requests

CVSS Score

9.1

EPSS Score

0.0%

EPSS Percentile

0th

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.

CWE	CWE-288
Vendor	threemammals
Product	ocelot
Published	Jun 30, 2026

Stay Ahead of the Next One

Get instant alerts for threemammals ocelot

Be the first to know when new critical vulnerabilities affecting threemammals ocelot are published — delivered to Slack, Telegram or Discord.

Get Free Alerts → Free · No credit card · 60 sec setup

CVSS v3 Breakdown

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

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

None

Affected Versions

ThreeMammals / Ocelot

0 ≤ 24.1.0

References

NVD ↗ CVE.org ↗ EPSS Data ↗

github.com: https://github.com/ThreeMammals/Ocelot/issues/2403 github.com: https://github.com/ThreeMammals/Ocelot/pull/2406 github.com: https://github.com/ThreeMammals/Ocelot/commit/f156fd4017ca25025fffdad8ec56c1d657dfb402 vulncheck.com: https://www.vulncheck.com/advisories/ocelot-ip-allow-block-list-bypass-for-websocket-upgrade-requests

Credits

George Chen