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CVE-2026-19377

Improper certificate validation in Cato Client tunnel handshake

No known exploitation. EPSS puts it in the 0th percentile. Fixed versions are out.

CVSS —Not scoredEPSS percentile0th<0.1% chance in 30 daysCISA KEVNot listedNo confirmed exploitation
No public exploit knownFix5 products5 fixed builds listed below

Published Updated Sources: CVE.org, NVD

NVD CVE.org

What to do

Find your product and version, then upgrade to the build on the right.

  • Cato Networks Cato Client for WindowsAffected: < 6.12.6Upgrade to: 6.12.6Stated by: CVE record
  • Cato Networks Cato Client for macOSAffected: < 6.1.1Upgrade to: 6.1.1Stated by: CVE record
  • Cato Networks Cato Client for LinuxAffected: < 5.8.1Upgrade to: 5.8.1Stated by: CVE record
  • Cato Networks Cato Client for iOSAffected: < 5.9Upgrade to: 5.9Stated by: CVE record
  • Cato Networks Cato Client for AndroidAffected: < 5.6.2Upgrade to: 5.6.2Stated by: CVE record

Versions as the sources state them. Full version matrix after sign-in

What it is

From the CVE record

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.

In plain language

No plain-language summary for this CVE yet.

Exploitation

Where each signal puts this CVE on the scale from published to confirmed exploited.

EPSS0th
CISA KEV

Not in the catalog. CISA has not confirmed exploitation.

Public exploits

No public exploit or proof of concept found in the sources we track.

EPSS

<0.1% chance of exploitation activity in the next 30 days, which ranks it in the 0th percentile of scored CVEs.

Exploit Prediction Scoring System, FIRST.org. A probability, not a confirmation.

Lifecycle

6 events over 1 day, from the signal feeds we watch.

  1. Record updated
  2. Publishedweakness classified, att&ck mapped, record updated, record updated

Affected products

Technical detail

Weaknesses

ATT&CK techniques

Mapped from the weaknesses above (CWE to ATT&CK), not observed in attacks.

Sources

References in the record

Watch the software you run.

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We'll flag the next CVE, public exploit or patch for Cato Client for Windows, not every advisory.