CVE-2021-20864 Auth bypass in ELECOM routers

High 8.8 Published 1 Dec 2021 Updated 3 Aug 2024

Network-adjacent attackers can bypass access controls to enable Telnet and execute arbitrary OS commands on ELECOM routers.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Local or same network only
Victim action needed: Not needed
Fix: None listed

What is CVE-2021-20864?

CVE-2021-20864 is a high-severity authentication bypass vulnerability in ELECOM routers, published on 1 Dec 2021. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

Improper access control vulnerability in ELECOM routers (WRC-1167GST2 firmware v1.25 and prior, WRC-1167GST2A firmware v1.25 and prior, WRC-1167GST2H firmware v1.25 and prior, WRC-2533GS2-B firmware v1.52 and prior, WRC-2533GS2-W firmware v1.52 and prior, WRC-1750GS firmware v1.03 and prior, WRC-1750GSV firmware v2.11 and prior, WRC-1900GST firmware v1.03 and prior, WRC-2533GST firmware v1.03 and prior, WRC-2533GSTA firmware v1.03 and prior, WRC-2533GST2 firmware v1.25 and prior, WRC-2533GST2SP firmware v1.25 and prior, WRC-2533GST2-G firmware v1.25 and prior, and EDWRC-2533GST2 firmware v1.25 and prior) allows a network-adjacent unauthenticated attacker to bypass access restriction, and to start the telnet service and execute an arbitrary OS command via unspecified vectors.

Which versions are affected by CVE-2021-20864?

It affects 14 products.

Products include Elecom Edwrc-2533gst2 Firmware, Elecom Wrc-1167gst2 Firmware, Elecom Wrc-1167gst2a Firmware, Elecom Wrc-1167gst2h Firmware, Elecom Wrc-1750gs Firmware, Elecom Wrc-1750gsv Firmware and 8 more.

How do I fix CVE-2021-20864?

No fix has been published for CVE-2021-20864 yet. Limit exposure of the affected software until one is available.

Upgrade, and rotate credentials and sessions that may have been exposed. More about Authentication bypass.

Is CVE-2021-20864 being exploited?

There is no known exploitation of CVE-2021-20864 in the wild and no public exploit code.

Sources

Also known as GHSA-3p76-j79h-ff2w.