CVE-2026-74232: Embedded Malicious Code in Zbtlink L3_V2_8
Description
Multiple Zbtlink and MoreQuick device firmware versions contain a backdoor implant named 'yunmgrd' that listens on an unauthenticated cleartext UDP channel to a hardcoded command-and-control server. This vulnerability allows a remote attacker on the network path to hijack the channel and execute arbitrary commands as root, modify DNS entries, exfiltrate PPPoE credentials, and open reverse SSH tunnels. The CVSS 4.0 score is 9.3, indicating critical severity. No official patch or remediation guidance is currently available.
CVSS v4.0
Score 9.3critical
Affected software
Zbtlink
L3_V2_8
Zbtlink
WE826-T2
Zbtlink
ZBT-7628
Zbtlink
ZBT-ZBT7621
MoreQuick
MQAC-7620
MoreQuick
MQAC-7620A
MoreQuick
MQAP-7620
MoreQuick
MQAP-7620A
MoreQuick
MQAP-7628
AP522
AP7628
APG721B
HC5661A
HK300
MAP-N10
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The affected firmware versions of Zbtlink L3_V2_8 and various related devices ship with a backdoor implant 'yunmgrd' accessible via an unauthenticated cleartext UDP channel to a hardcoded C2 server. This implant enables remote attackers on the network path to hijack communications and execute arbitrary commands with root privileges. Additional impacts include DNS modification, credential exfiltration, and establishing reverse SSH tunnels. The vulnerability is critical with a CVSS 4.0 score of 9.3. No vendor advisory or patch information is currently provided.
Potential Impact
An unauthenticated remote attacker on the network path can hijack the backdoor UDP channel to execute arbitrary commands as root on affected devices. This can lead to unauthorized DNS changes, theft of PPPoE credentials, and creation of reverse SSH tunnels, potentially compromising network integrity and confidentiality.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is available, network segmentation and monitoring for unusual UDP traffic to known C2 servers may help reduce risk, but no vendor-provided mitigation is documented.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- VulnCheck
- Date Reserved
- 2026-08-14T18:01:19.917Z
- Cvss Version
- 4.0
- State
- PUBLISHED
Threat ID: 6a9036a9acd9273b494a2f23
Added to database: 08/27/2026, 13:07:53 UTC
Last enriched: 09/09/2026, 10:37:23 UTC
Last updated: 10/10/2026, 18:48:22 UTC
Views: 66
Community Reviews
0 reviewsCrowdsource mitigation strategies, share intel context, and vote on the most helpful responses. Sign in to add your voice and help keep defenders ahead.
Want to contribute mitigation steps or threat intel context? Sign in or create an account to join the community discussion.
Actions
Updates to AI analysis require Pro Console access. Upgrade inside Console → Billing.
Need more coverage?
Upgrade to Pro Console for AI refresh and higher limits.
For incident response and remediation, OffSeq services can help resolve threats faster.
Latest Threats
Check if your credentials are on the dark web
Instant breach scanning across billions of leaked records. Free tier available.