CVE-2026-102761

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BaseFortify

Publication date: 2026-09-29

Last updated on: 2026-09-30

Assigner: Eclipse Foundation

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.

CVSS Scores

EPSS Scores

Probability:
Percentile:

Meta Information

Published

2026-09-29

Last Modified

2026-09-30

Generated

2026-10-19

AI Q&A

2026-09-29

EPSS Evaluated

2026-10-18

NVD

CVE-2026-102761

EUVD

EUVD-2026-89210

Affected Vendors & Products

Vendor	Product	Version / Range
Eclipse	Foundation	NetX Duo 6.2.0

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-787	The product writes data past the end, or before the beginning, of the intended buffer.

Attack-Flow Graph

Executive Summary

This vulnerability involves NetX Duo's WebSocket client incorrectly handling masked server frames split across multiple packets. The client resets the unmasking cursor to the start of the first packet each time it processes a chained packet, causing the XOR loop to corrupt memory by writing beyond the intended payload area into the second packet's control block. The attacker can control the corruption via the four-byte WebSocket masking key.

Detection Guidance

Detection requires monitoring for abnormal WebSocket traffic patterns or packet corruption in NetX Duo implementations. Inspect network traffic for fragmented WebSocket frames with unusual masking key usage. Check for crashes or memory corruption in applications using NetX Duo WebSocket client.

Impact Analysis

This flaw could allow remote attackers to execute arbitrary code or cause denial-of-service conditions by sending specially crafted WebSocket frames. The high CVSS score (9.3) indicates severe impact, including potential data breaches or system compromise if exploited.

Compliance Impact

The vulnerability allows attacker-controlled corruption of WebSocket data due to improper unmasking cursor handling in NetX Duo. This could lead to unauthorized data modification or exposure, potentially violating confidentiality and integrity requirements in GDPR and HIPAA.

Mitigation Strategies

Apply patches from NetX Duo maintainers immediately. Disable WebSocket client functionality if not required. Implement network-level filtering to block malformed WebSocket frames. Monitor for exploitation attempts and update affected systems as soon as fixes are available.

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