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CVE-2026-11834: Unauthenticated Command Injection via DHCP Option Handling in Multiple TP-Link Routers

• Severity: high (CVSS 8.7 v4.0)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.7% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-06-22 · updated 2026-06-26
• Weakness: CWE-78

Description

A command injection vulnerability has been identified in the DHCP option processing logic in multiple TP-Link router models, due to insufficient validation of externally supplied DHCP option data. An adjacent attacker may exploit this vulnerability by supplying crafted DHCP responses, potentially resulting in unauthorized command execution during device initialization or provisioning workflows. This typically occurs when the device is in a factory-default or unconfigured state. Successful exploitation may allow an adjacent, unauthenticated attacker to execute arbitrary commands with elevated privileges, potentially leading to full compromise of the affected device and unauthorized administrative control.

Affected products

• TP-Link Systems Inc. Archer C20 v6: before V6_260608 — fixed in V6_260608
• TP-Link Systems Inc. Archer C20 v5: before EU_V5_260317; before US_V5_260419 — fixed in EU_V5_260317, US_V5_260419
• TP-Link Systems Inc. Archer MR200 v07: before 1.3.0 Build 250605 — fixed in 1.3.0 Build 250605
• TP-Link Systems Inc. Archer MR200 v8: before 1.5.0 Build 260605 — fixed in 1.5.0 Build 260605
• TP-Link Systems Inc. Archer VR2100 v1: before EU_V1_260330 — fixed in EU_V1_260330
• TP-Link Systems Inc. TL-MR6400 v7: before 1.7.0 Build 260413 — fixed in 1.7.0 Build 260413
• TP Link Systems Inc. Archer MR402 v1: before 1.5.0 Build 260605 — fixed in 1.5.0 Build 260605

How to fix

Upgrade to a fixed version: TP-Link Systems Inc. Archer C20 v6 V6_260608; TP-Link Systems Inc. Archer C20 v5 EU_V5_260317, US_V5_260419; TP-Link Systems Inc. Archer MR200 v07 1.3.0 Build 250605; TP-Link Systems Inc. Archer MR200 v8 1.5.0 Build 260605; TP-Link Systems Inc. Archer VR2100 v1 EU_V1_260330; TP-Link Systems Inc. TL-MR6400 v7 1.7.0 Build 260413; TP Link Systems Inc. Archer MR402 v1 1.5.0 Build 260605. Check the vendor advisory for mitigations.

References

• https://mattg.systems/posts/cve-2026-11834/
• https://www.tp-link.com/en/support/download/archer-c20/
• https://www.tp-link.com/en/support/download/archer-mr200/#Firmware
• https://www.tp-link.com/en/support/download/archer-mr402/#Firmware
• https://www.tp-link.com/en/support/download/archer-vr2100/#Firmware
• https://www.tp-link.com/en/support/download/tl-mr6400/v7/#Firmware
• https://www.tp-link.com/us/support/download/archer-c20/
• https://www.tp-link.com/us/support/faq/5141/

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