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VulnerabilityPublished Updated

CVE-2026-10099: XX-Net · Improper Validation of Syntactic Correctness of Input

Affects XX-NetSource CVE Database V5

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Not known to be exploited · CVSS 4.0 Medium.

Data as of 8 Nov 2026, 14:20 UTC

CVSS 3.1 base score
4.0Medium
How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none
CVSS scores by source
CNA (VulnCheck)CVSS 3.14.0
CNA (VulnCheck)CVSS 4.05.1
CISA SSVC
Exploitation
No evidence of active exploitation and no public proof of concept
Automatable
Attackers cannot reliably automate steps 1–4 of the kill chain
Technical impact
Limited control over the software or limited information exposure

CISA SSVC assessment, 2026-06-01.

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

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 29 May 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 8 Nov 2026.

What to do

Affected software

ProductAffectedFixed in
XX-netXX-NetAffected
  • <=5.16.6
  • =0
Fixed in–

AI-suggested

Users should monitor vendor advisories for updates. Until a fix is available, cautious use of the affected versions is advised. There are no vendor advisories indicating that the issue is already mitigated or requires no action.

Description

XX-Net version 5.16.6 and earlier contain a vulnerability in the WebSocket frame parsing logic within simple_http_server.py. The server incorrectly processes unmasked WebSocket frames by always reading 4 bytes as a masking key regardless of the MASK bit, leading to corrupted application data. This flaw causes improper XOR decoding of the payload and lacks validation of RSV bits, opcode, and FIN fragmentation flags.

References

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