CVE-2026-3841: TP-Link Systems TL-MR6400 v5.3 · OS Command Injection
Affects TP-Link Systems TL-MR6400 v5.3Source CVE Database V5
Not known to be exploited · CVSS 8.5 High : upgrade to 1.9.0 Build 260108 soon.
Data as of 30 Oct 2026, 11:52 UTC
- EPSS
- 1.7% chance of exploitation in 30 days – higher than 77% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 1.9.0 Build 260108
CVSS:4.0/AV:A/AC:L/AT:N/PR:H/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:NExploitation evidence
Disclosed: evidence found.
CVE published 12 Mar 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by 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 30 Oct 2026.
What to do
Upgrade TP-Link Systems TL-MR6400 v5.3 to 1.9.0 Build 260108.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| TP-Link Systems Inc.TL-MR6400 v5.3 | Affected
| Fixed in
|
AI-suggested
To mitigate CVE-2026-3841, organizations should first verify if they are using the TP-Link TL-MR6400 v5.3 firmware and restrict Telnet access to trusted administrators only, ideally disabling Telnet entirely if not required. Network segmentation should be enforced to limit access to management interfaces. Strong authentication mechanisms and credential management policies must be implemented to prevent unauthorized privilege escalation. Monitoring and logging of Telnet sessions should be enhanced to detect suspicious activities. Since no patches are currently available, consider deploying compensating controls such as firewall rules to block Telnet access from untrusted networks and use VPNs or secure management channels instead. Regularly check for firmware updates from TP-Link and apply security patches promptly once released. Additionally, conduct internal audits to identify any unauthorized changes or signs of compromise on affected devices. Employ network intrusion detection systems tuned to detect command injection attempts or anomalous Telnet traffic patterns.
Description
CVE-2026-3841 is a high-severity OS command injection vulnerability in the Telnet CLI of TP-Link TL-MR6400 v5.3 routers. It arises from improper sanitization of input data during certain CLI operations, allowing an authenticated attacker with elevated privileges to execute arbitrary system commands. Exploitation can lead to full device compromise, affecting confidentiality, integrity, and availability. No user interaction is required, but elevated privileges and network access via Telnet are necessary. Although no known exploits are currently in the wild, the vulnerability poses a significant risk due to the critical nature of the device and its role in network infrastructure. Organizations using this router model should prioritize patching or mitigating this issue. Countries with widespread use of TP-Link networking equipment and strategic reliance on such devices are at higher risk.