Do Son 
TL;DR
Security experts have disclosed a critical TP-Link Kasa vulnerability, identified as CVE-2026-76784. This high-severity flaw affects multiple smart plugs, switches, and bulbs, allowing attackers to hijack local device controls. Users must apply the latest firmware updates immediately to secure their smart home networks.
- CVE: CVE-2026-76784
- CVSS: 8.7 (High · CVSSv4)
- Product: TP-Link Systems Inc. HS103P3 / HS103P4 v5
- Affected: < 1.1.3 Build 250908 Rel.112508, < 1.1.1 Build 250908 Rel.112508, < 1.0.3 Build 240529 Rel.145252, < 1.1.2 Build 241220 Rel.171333, < 1.1.2 Build 241220 Rel.173321, < 1.1.1 Build 250908 Rel.112526 (+13 more)
- Impact: Insufficient Cryptographic Protections in Local Device Communication Protocol on Multiple TP-Link Kasa Smart Home Devices
- Status: No confirmed exploitation yet
- Patched in: 1.1.3 Build 250908 Rel.112508, 1.1.1 Build 250908 Rel.112508, 1.0.3 Build 240529 Rel.145252, 1.1.2 Build 241220 Rel.171333 (+15 more)
- Action: Update to 1.1.3 Build 250908 Rel.112508, 1.1.1 Build 250908 Rel.112508, 1.0.3 Build 240529 Rel.145252, 1.1.2 Build 241220 Rel.171333 (+15 more) now
Why the Vulnerability Matters
Smart home ecosystems require strong local encryption to prevent malicious interference. TP-Link warns that this flaw carries a high CVSS v4.0 score of 8.7. According to the official advisory, “Successful exploitation could allow an attacker to manipulate the operational state of an affected device, resulting in unauthorized state changes, disruption of normal device functionality or a denial-of-service condition.” Currently, TP-Link has not published specific estimates regarding affected user counts. Furthermore, researchers have not confirmed any active exploitation in the wild or public proof-of-concept availability.
How the Attack Works
The core issue stems from insufficient cryptographic protections in the local device communication protocol. When devices exchange control messages on the local network, the weak encryption fails to validate message authenticity properly. Consequently, an adjacent network attacker can intercept these communications. After capturing the traffic, the attacker can replay or forge locally exchanged control messages. This process grants them direct, unauthorized control over the targeted appliance.
Affected Versions
This TP-Link Kasa vulnerability impacts a broad range of hardware models. Affected smart plugs and switches include the HS103P3, HS300, EP10, EP25, EP40A, and KP303 series. The flaw also extends to the KL125 smart bulb.
Mitigation and Patch Steps
The manufacturer has released firmware updates for all impacted models. Administrators and homeowners must download and apply the specific fixed versions corresponding to their hardware. For instance, HS103P3 units require firmware version 1.1.3 Build 250908. For a complete list of fixed builds and upgrade details, consult the official TP-Link security advisory FAQ 5267. Users should rely on the official Kasa applications to deploy these patches securely.
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