High · CVSS 8.1CVE-2026-25687

ZCC race condition in ZPA tunnel handlerCVE-2026-25687

Answer in brief

CVE-2026-25687 records a High severity (CVSS 8.1) vulnerability in ZCC race condition in ZPA tunnel handler. The current sources do not mark it as known exploited. The current feed maps Zscaler/Client Connector (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Sep 14, 2026Updated Sep 18, 2026Source checked Oct 29, 2026First seen by HOL Sep 14, 2026Material review Sep 18, 2026

Upstream Advisory

Key facts

Risk: High · CVSS 8.1
Exploitation: Not marked as known exploited
Affected software: 1 mapped package or product
Fix availability: Available

Why this deserves its current priority

CVSS is 8.1. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps Zscaler/Client Connector (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
Zscaler/Client Connectorgeneric	>=4.6 <4.6.0.486 \|\| >=4.7 <4.7.0.350 \|\| >=4.8 <4.8.0.267 \|\| >=4.9 <4.9.0.412	4.6.0.486, 4.7.0.350, 4.8.0.267, 4.9.0.412

Recommended response

Check inventory. Check lockfiles and deployed manifests for Zscaler/Client Connector.
Review the reported fix. Update Zscaler/Client Connector to 4.6.0.486 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Sep 14, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Sep 18, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Sep 14, 2026

Sources and claim methodology

Source referencehelp.zscaler.com

Upstream source description

A race condition in the ZPA tunnel handler of affected versions of Zscaler Client Connector (ZCC) allows a heap corruption, resulting in a denial of service (client crash) and potentially arbitrary code execution in the context of the ZCC process.

Quoted source text, attributed separately from HOL analysis.