Critical 9.1Published Jun 30, 2026

CVE-2026-58172Ocelot - IP Allow/Block List Bypass for WebSocket Upgrade Requests

Updated under an hour ago (Oct 27, 2026, 6:50 AM ET)

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Every CVE for ThreeMammals Ocelot

Exploited in the last 30 days

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.

CVSS: 9.1 CRITICAL (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
Weakness (CWE): CWE-288
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: VulnCheck
NVD analysis: Deferred
Record last updated: Jul 14, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

ThreeMammals Ocelot threemammals:ocelot (from the name)	through 24.1.0; f156fd4017ca25025fffdad8ec56c1d657dfb402 not affected	CNA record

References

References

https://github.com/ThreeMammals/Ocelot/issues/2403	technical-description, exploit
https://github.com/ThreeMammals/Ocelot/pull/2406	issue-tracking
https://github.com/ThreeMammals/Ocelot/commit/f156fd4017ca25025fffdad8ec56c1d657dfb402	patch
https://www.vulncheck.com/advisories/ocelot-ip-allow-block-list-bypass-for-websocket-upgrade-requests	third-party-advisory

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.