CVE-2021-35394Known exploitationPublic exploitNetwork attack vector

Unauthenticated command execution via unchecked UDP commands

Published Aug 16, 2021 · Updated Oct 21, 2025

Command injection in Realtek Jungle SDK 2.0 through 3.4.14B allows remote attackers to execute arbitrary commands through UDPServer. The MP Daemon's UDPServer performs insufficient legality checks on commands received from clients, allowing crafted UDP requests to reach command-execution and buffer-overflow paths. No authentication or user interaction is required, and successful exploitation can take over an affected router or crash the service.

CVSS severity9.8
Critical
EPSS probability99.86%
Next 30 days · Sep 16, 2026
Known exploitationReported
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Command injection in Realtek Jungle SDK 2.0 through 3.4.14B allows remote attackers to execute arbitrary commands through UDPServer. The MP Daemon's UDPServer performs insufficient legality checks on commands received from clients, allowing crafted UDP requests to reach command-execution and buffer-overflow paths. No authentication or user interaction is required, and successful exploitation can take over an affected router or crash the service.

The record

CVE
CVE-2021-35394
Published
Aug 16, 2021
Updated
Oct 21, 2025
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-78, CWE-77, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 1, 2021Exploitation reportedBotnet malware delivery through UDPServer exploitation
  2. Aug 16, 2021CVE publishedPublication date reported by the CVE source.
  3. Oct 21, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

9.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationReported
Public exploitPublished

Weakness, pattern, technique

CWE-78Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')
CWE-77Improper Neutralization of Special Elements used in a Command ('Command Injection')
T1190Exploit Public-Facing Application

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Reported exploitation

Technologies

Your stack

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Your stack

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