---
id: CVE-2026-10099
title: >-
  XX-Net V5.16.6 contains a WebSocket frame parsing vulnerability in the
  WebSocket_receive_worker routine of simple_http_server.py that allows
  attackers to cause corrupted application data by sending unmasked WebSocket
  frames
summary: >-
  XX-Net V5.16.6 contains a WebSocket frame parsing vulnerability in the
  WebSocket_receive_worker routine of simple_http_server.py that allows
  attackers to cause corrupted application data by sending unmasked WebSocket
  frames. The server u…
severity: medium
cvss: 4
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N'
cwe:
  - CWE-1286
published: '2026-05-29'
updated: '2026-10-06'
sourceUpdated: '2026-10-06T22:10:00.247'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-10099'
references:
  - url: >-
      https://github.com/XX-net/XX-Net/commit/a68b972a84ed6e52df9f30237cf47493b9231b53
    label: disclosure@vulncheck.com
  - url: 'https://github.com/XX-net/XX-Net/issues/14169'
    label: disclosure@vulncheck.com
  - url: 'https://github.com/XX-net/XX-Net/pull/14170'
    label: disclosure@vulncheck.com
  - url: >-
      https://www.vulncheck.com/advisories/xx-net-websocket-frame-parsing-data-corruption-via-simple-http-server-py
    label: disclosure@vulncheck.com
tags:
  - nvd
epss: 0.00125
epssPercentile: 0.01928
ingestedAt: '2026-10-06T22:23:15.927Z'
---

## Overview

XX-Net V5.16.6 contains a WebSocket frame parsing vulnerability in the WebSocket_receive_worker routine of simple_http_server.py that allows attackers to cause corrupted application data by sending unmasked WebSocket frames. The server unconditionally reads 4 bytes as a masking key regardless of whether the MASK bit is set in the frame header, causing the first 4 bytes of payload to be consumed as a mask key and the remaining payload to be incorrectly XOR-decoded, resulting in data corruption alongside missing RSV bit, opcode, and FIN fragmentation validations.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.