CVE-2021-35394: Realtek Jungle SDK Remote Code Execution Vulnerability
Advisory generated from the CVE record, CISA, Exploit Observer and VEDAS: what it is, whether it is exploited, who is affected, and how to fix and detect it.
Generated by VEDAS. Scores as of 2026-11-08 00:03 UTC. Rebuilt every few hours from cve-scores, CISA KEV and vedas-signatures. How this works and its limits.
What it is
Realtek Jungle SDK version v2.x up to v3.4.14B provides a diagnostic tool called ‘MP Daemon’ that is usually compiled as ‘UDPServer’ binary. The binary is affected by multiple memory corruption vulnerabilities and an arbitrary command injection vulnerability that can be exploited by remote unauthenticated attackers.
Description quoted from the CVE record (assigned by mitre, published 2021-08-16).
Weakness: CWE-78 Improper Neutralization of Special Elements used in an OS Command (‘OS Command Injection’)
How it can be exploited
Exploitable over the network with low attack complexity needing no privileges and no user interaction. Impact: confidentiality high, integrity high, availability high. CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CISA assessment (SSVC): CISA assesses exploitation as active. Automatable: yes. Technical impact: total.
- On CISA KEV since
- 2021-12-10
- US federal deadline
- 2021-12-24
- Ransomware use
- Not known
Public exploit evidence (Exploit Observer)
Exploit Observer found 1 Nuclei template and 1 code repository naming this CVE.
Code repositories that name a CVE are often scanners, copies or fakes, and some are malware. Read the code before running anything.
See all 8 references on Exploit Observer
Live scores
- EPSS
- 0.999
very likely to be attacked soon - VEDAS
- 0.982
strong exploit evidence - On CISA KEV
- Yes, since 2021-12-10
- Detection rule
- No public rule yet
Thin horizontal line: the “likely exploited” threshold (EPSS 0.10, VEDAS 0.5). Shaded “no data” areas are periods when cve-scores did not publish.
Who is affected
| Product | Affected | Not affected |
|---|---|---|
| Not stated | versions not stated in the record | Not stated |
Version ranges exactly as the CVE record states them. “Before X” means X is the first fixed version.
How to fix it
CISA required action: Apply updates per vendor instructions.
Vendor guidance:
How to detect it
There is no open VEDAS detection rule for this bug yet. It is listed on the detection gaps page if CISA has confirmed attacks.
Advisories on this CVE
- “ClingSTUN” Linux backdoor turns IoT devices into proxy nodes and hides its C2 inside public STUN traffic (full advisory)
References
Government sources
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-35394 (government-resource)
Other references
- https://www.securityfocus.com/archive/1/534765 (x_refsource_MISC)
- https://www.realtek.com/en/cu-1-en/cu-1-taiwan-en (x_refsource_MISC)
- https://www.realtek.com/images/safe-report/Realtek_APRouter_SDK_Advisory-CVE-2021-35392_35395.pdf (x_refsource_MISC)
- https://www.iot-inspector.com/blog/advisory-multiple-issues-realtek-sdk-iot-supply-chain (x_refsource_MISC)
Other databases
Where this comes from
This advisory is generated automatically by VEDAS from: CVE.org record, CISA KEV, cve-scores (EPSS and VEDAS), Exploit Observer. Text in quotes is reproduced from the source; everything else is a fixed template filled with source fields. Nothing here is written by a language model. Check the vendor advisory before acting, and read how VEDAS and Exploit Observer work, and their limits.
Supporting partners
