Medium 6.0Published Oct 15, 2026

CVE-2026-19377Improper certificate validation in Cato Client tunnel handshake

Updated under an hour ago (Oct 27, 2026, 11:00 AM ET)

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It affects Cato Networks Cato Client for Windows and 4 other products. Add what you run to find out whether that includes you.

No exploitation reported and no EPSS estimate yet.

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Every CVE for Cato Networks Cato Client for Windows

Exploited in the last 30 days

Improper certificate validation in the tunnel handshake in Cato Client allows a man-in-the-middle attacker to impersonate a Cato Point of Presence (PoP) server and intercept or modify tunnel traffic.

CVSS: 6.0 MEDIUM (v4.0, CNA)CVSS:4.0/AV:A/AC:L/AT:P/PR:N/UI:N/VC:L/VI:H/VA:N/SC:N/SI:N/SA:N
Weakness (CWE): CWE-295
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: Cato
NVD analysis: Deferred
Record last updated: Oct 15, 2026
First seen by InfoSec Signals: Oct 15, 2026

Affected products

Affected products

Cato Networks Cato Client for Windows cato_networks:cato_client_for_windows (from the name)	before 6.12.6	CNA record
Cato Networks Cato Client for macOS cato_networks:cato_client_for_macos (from the name)	before 6.1.1	CNA record
Cato Networks Cato Client for Linux cato_networks:cato_client_for_linux (from the name)	before 5.8.1	CNA record
Cato Networks Cato Client for iOS cato_networks:cato_client_for_ios (from the name)	before 5.9	CNA record
Cato Networks Cato Client for Android cato_networks:cato_client_for_android (from the name)	before 5.6.2	CNA record

References

References

https://knowledge.catonetworks.com/docs/security-vulnerability-cve-2026-19377-that-impacts-cato-client-versions	vendor-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.