CVE-2021-35394
CriticalExploitedPublic exploitRealtek Jungle SDK version v2.x up to v3.4.14B provides a diagnostic tool called 'MP Daemon' that is usually compiled as 'UDPServer' binary.
Published Aug 16, 2021 · Updated Nov 7, 2025
Key Facts
Patch immediately- CVE-2021-35394 is a critical-severity vulnerability (CVSS 9.8 v3.1) affecting Rtl819x Jungle Software Development Kit (Realtek).
- It is exploited in the wild, listed in CISA KEV, Industry KEV feed, CIRCL KEV, ENISA EUVD since Aug 27, 2021. Public exploit code is available.
- EPSS estimates a 100% probability of exploitation in the next 30 days.
- Fixed versions are available, including Rtl819x Jungle Software Development Kit <=3.4.14b, Rtl819x Jungle Software Development Kit 3.4.14b.
- Brandefense priority: patch immediately, because it is listed as exploited in the wild.
CVSS v3.1
9.8
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS (30-day exploit likelihood)
100%
Higher than 99.9% of all scored CVEs
Exploited in the wild
Yes
4 catalog listings
Public exploit code
Available
Proof-of-concept or weaponized module
Get the full CVE-2021-35394 brief as a PDF
Every affected product and fixed release, exploitation status and a first 24 hours response checklist, emailed within minutes.
Description
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.
Known-Exploited Catalog Listings
| Catalog | Added | Remediation due | Ransomware use |
|---|---|---|---|
| CISA KEV | Dec 10, 2021 | Dec 24, 2021 | Not reported |
| Industry KEV feed | Aug 27, 2021 | Dec 24, 2021 | Not reported |
| CIRCL KEV | Dec 10, 2021 | Dec 24, 2021 | Not reported |
| ENISA EUVD | Dec 10, 2021 | n/a | Not reported |
Required action: Apply updates per vendor instructions.
Affected Products
1 affected entries in total| Product | Affected versions | Fixed in |
|---|---|---|
| Rtl819x Jungle Software Development KitRealtek | See advisory | 3.4.14b |
Patched Releases
Rtl819x Jungle Software Development Kit
<=3.4.14b
Timeline
Publicly disclosed
Aug 16, 2021
Added to Industry KEV feed
Aug 27, 2021
Added to CISA KEV
Dec 10, 2021
Added to CIRCL KEV
Dec 10, 2021
Added to ENISA EUVD
Dec 10, 2021
Last updated
Nov 7, 2025
Weakness Type
- CWE-78 Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')
References
- advisoryhttps://www.securityfocus.com/archive/1/534765
- patchhttps://www.realtek.com/en/cu-1-en/cu-1-taiwan-en
- patchhttps://www.realtek.com/images/safe-report/Realtek_APRouter_SDK_Advisory-CVE-2021-35392_35395.pdf
- exploitVulnCheck exploitation report
- exploitVulnCheck exploitation report
FAQ
Common Questions.
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.
Affected: Rtl819x Jungle Software Development Kit (Realtek). The full list is in the CVE brief.
It is exploited in the wild, listed in CISA KEV, Industry KEV feed, CIRCL KEV, ENISA EUVD since Aug 27, 2021.
Yes. It was added on Dec 10, 2021 with a federal remediation due date of Dec 24, 2021.
Public exploit code is available.
Fixed versions are available, including Rtl819x Jungle Software Development Kit <=3.4.14b, Rtl819x Jungle Software Development Kit 3.4.14b.
Brandefense priority: patch immediately, because it is listed as exploited in the wild.
Is CVE-2021-35394 Running On Your Attack Surface?
Brandefense maps vulnerabilities like this one to your internet-facing assets and tells you exactly where to patch.
Request A Demo