web analytics
Home » Technology » FritzOS 7.02: AVM launches Fragattack security patch for mini routers

FritzOS 7.02: AVM launches Fragattack security patch for mini routers

AVM’s mini router, the FritzBox 4020, is now getting another update. Fritz OS 7.02 is a maintenance update with security-relevant changes – therefore the update is strongly recommended to all owners of the 4020. The FritzBox 4020 has been one of the smallest routers available since it was introduced almost six years ago – it is significantly smaller than its FritzBox colleagues. Now the cheap and popular router is getting a new software update. AVM is now addressing the so-called Fragattack problem for the router as it has for many other models in recent weeks. You can find all changes at the end of the article in the list of release notes for the Fritzbox 4020.

This is the point at issue

FragAttack goes back to a design flaw in worldwide WLAN standards as far back as 1997. The abbreviation stands for Fragmentation and Aggregation Attack, an attack scenario that has been known since the beginning of the year. All WiFi-enabled devices are affected, from routers to smartphones. However, this design flaw is difficult to exploit – according to security researchers, there was no urgent need to provide quick updates. AVM is now patching this vulnerability bit by bit for routers, repeaters and Co. and eliminates the programming errors. The update is therefore recommended to all users.

Update function or FTP

You can update your FritzBox easily using the online update function. To do this, select “Update” or “Update firmware” in the wizard. Alternatively, the Update file on ftp.avm.de ready. The image contains the current FritzOS 7.02 and is only intended for the FritzBox 4020. With each new FritzOS update, AVM also updates the security functions and therefore recommends performing the update for all devices.

FritzOS 7.02 for FritzBox 4020


  • Improvement – Updated Trusted Root Certification Authorities


  • Fixed – Vulnerabilities in the handling of incoming fragmented packets and aggregated MPDUs (A-MPDU) fixed (“Fragattack”)