CVE-2026-102761

NetX Duo WebSocket Client Buffer Overwrite via Masking Key

Published Sep 29, 2026 CVSS 4.0 · 9.3 Critical EPSS < 1% KEV · Not listed
Description
NetX Duo's WebSocket client resets the unmasking cursor to the first `NX_PACKET` each time it advances through a chained packet, while the loop's upper bound belongs to the current packet. With the standard contiguous packet-pool layout, a masked server frame split across two packets therefore drives the XOR loop through the first packet's unused payload area and on through the second packet's `NX_PACKET` control block.



The four-byte WebSocket masking key controls the bytes written, so the corruption is attacker-chosen rather than incidental.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}

Type Values Removed Values Added
First Time appeared Eclipse
Eclipse netx Duo
Vendors & Products Eclipse
Eclipse netx Duo
Type Values Removed Values Added
Title NetX Duo WebSocket Client Buffer Overwrite via Masking Key
Type Values Removed Values Added
Description NetX Duo's WebSocket client resets the unmasking cursor to the first `NX_PACKET` each time it advances through a chained packet, while the loop's upper bound belongs to the current packet. With the standard contiguous packet-pool layout, a masked server frame split across two packets therefore drives the XOR loop through the first packet's unused payload area and on through the second packet's `NX_PACKET` control block. The four-byte WebSocket masking key controls the bytes written, so the corruption is attacker-chosen rather than incidental.
Weaknesses CWE-787
References
Metrics cvssV4_0

{'score': 9.3, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
eclipse
Published
Updated
Sep 30, 2026, 8:41 PM
Reserved
Sep 29, 2026, 4:22 PM
Status
Awaiting Analysis
Published
Sep 29, 2026, 6:17 PM
Modified
Sep 30, 2026, 9:17 PM