CVE-2026-10099

Description

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.

Is your site exposed to CVE-2026-10099?

Run a free security scan — no signup, results in seconds.

CVSS v3.1 Score

4.0

MEDIUM

CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

EPSS — Exploit Prediction

0.0013

Probability of exploitation

0.03%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-1286 CWE-1286

References

Other References

https://github.com/XX-net/XX-Net/commit/a68b972a84ed6e52df9f30237cf47493b9231b53 https://github.com/XX-net/XX-Net/issues/14169 https://github.com/XX-net/XX-Net/pull/14170 https://www.vulncheck.com/advisories/xx-net-websocket-frame-parsing-data-corruption-via-simple-http-server-py

Frequently Asked Questions

What is CVE-2026-10099? +

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. It has a CVSS v3.1 base score of 4.0 (MEDIUM).

How severe is CVE-2026-10099? +

CVE-2026-10099 has a CVSS v3.1 score of 4.0 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0013, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-10099? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

Related Vulnerabilities

CVE-2026-0983

Denial-of-service condition in M-Files Server versions before 26.5.16015.0, before 26.2 LTS, and before 25.8 LTS SR3 allows an authenticated user …

CVE-2024-7954 9.8

The porte_plume plugin used by SPIP before 4.30-alpha2, 4.2.13, and 4.1.16 is vulnerable to an arbitrary code execution vulnerability. A …

CVE-2025-41719 8.8

A low privileged remote attacker can corrupt the webserver users storage on the device by setting a sequence of unsupported …

CVE-2026-50131 8.6

Fedify is a TypeScript library for building federated server apps powered by ActivityPub. Fedify previously addressed SSRF/internal network access in …

CVE-2026-6442 8.3

Improper validation of bash commands in Snowflake Cortex Code CLI versions prior to 1.0.25 allowed subsequent commands to execute outside …

CVE-2024-26507 7.8

An issue in FinalWire AIRDA Extreme, AIDA64 Engineer, AIDA64 Business, AIDA64 Network Audit v.7.00.6700 and before allows a local attacker …