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Vulnerabilities

Vulnerability · CVE-2026-19377

Improper certificate validation in Cato Client tunnel handshake

Published Oct 15, 2026 · catalog updated Oct 15, 2026 · Cato Networks Cato Client for Windows

Check if you run it

No confirmed exploitation is on record for CVE-2026-19377. EPSS is 0.08%. Act only if a listed version of Cato Networks Cato Client for Windows is installed.

Gaps on this record

  • No version range is stored. A customer cannot check an installed version against this record.
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
Medium6.0
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.08%
Remediation
Advisory link
Affected products
vendor Cato Networks Cato Client for Android · vendor Cato Networks Cato Client for Linux · vendor Cato Networks Cato Client for Windows · vendor Cato Networks Cato Client for iOS · vendor Cato Networks Cato Client for macOS

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.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • vendor Cato Networks Cato Client for Androidversion unspecified
  • vendor Cato Networks Cato Client for Linuxversion unspecified
  • vendor Cato Networks Cato Client for Windowsversion unspecified
  • vendor Cato Networks Cato Client for iOSversion unspecified
  • vendor Cato Networks Cato Client for macOSversion unspecified

How to fix CVE-2026-19377

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-19377. EPSS is 0.08%. Act only if a listed version of Cato Networks Cato Client for Windows is installed.

Which versions are affected?

Affected version ranges are not on this record. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-295: Improper Certificate Validation. EPSS 0.08%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Technology hubs

Windows security

Code

The project this record applies to. Exploit listings stay in References.

No public source repository is identified for this product.

Timeline

Detection, updates, and resolution for this record.

  1. Oct 15, 2026 · NIST NVD

    Detected

    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.

  2. Oct 15, 2026 · NIST NVD

    Updated

    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.

Sources

  • CIRCL Vulnerability LookupVulnerability recordCVE-2026-19377

    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.

    vulnerability.circl.lu
  • CVE.orgVulnerability recordCVE-2026-19377

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-19377

    30-day exploitation probability 0.1%

    first.org
  • NIST NVDVulnerability recordCVE-2026-19377

    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.

    nvd.nist.gov

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.