CVE-2020-26887

HIGH

FRITZ!Box 7490 Firmware < 7.21 - DNS Rebinding Protection Mechanism Bypass

Title source: llm
STIX 2.1

Exploitation Summary

EIP tracks 1 public exploit for CVE-2020-26887. PoCs published by RedTeam Pentesting GmbH.

AI-analyzed exploit summary The exploit demonstrates a DNS rebinding protection bypass in FRITZ!Box routers by using IPv6-mapped IPv4 addresses (::ffff:192.168.178.20) and loopback addresses (127.0.0.1) to circumvent the suppression of private IP DNS responses.

Description

FRITZ!OS before 7.21 on FRITZ!Box devices allows a bypass of a DNS Rebinding protection mechanism.

Exploits (1)

exploitdb WRITEUP
by RedTeam Pentesting GmbH · textremotehardware
https://www.exploit-db.com/exploits/49293

The exploit demonstrates a DNS rebinding protection bypass in FRITZ!Box routers by using IPv6-mapped IPv4 addresses (::ffff:192.168.178.20) and loopback addresses (127.0.0.1) to circumvent the suppression of private IP DNS responses.

Classification
Writeup 100%
Attack Type
Other
Complexity
Trivial
Reliability
Reliable
Target: FRITZ!Box 7.20 and below
No auth needed
Prerequisites: Access to a DNS server to configure specific resource records · A vulnerable FRITZ!Box router on the network
devstral-2 · analyzed Feb 16, 2026 Full analysis →

References (3)

Core 3
Core References
Vendor Advisory x_refsource_misc
https://en.avm.de/news/

Scores

CVSS v3 7.8
EPSS 0.0140
EPSS Percentile 69.0%
Attack Vector LOCAL
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Details

Status published
Products (1)
avm/fritz\!box_7490_firmware < 7.21
Published Oct 23, 2020
Tracked Since Feb 18, 2026