CVE-2020-1666 Junos OS Evolved: 'console log-out-on-disconnect' fails to terminate session on console cable disconnection
Attackers with physical console access can resume active sessions due to failed logout on disconnect, potentially gaining administrative privileges.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- A user has to click or open something
- Fix
- None listed
What is CVE-2020-1666?
CVE-2020-1666 is a medium-severity authentication bypass vulnerability in Juniper Junos Os Evolved, published on 16 Oct 2020. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Official description
The system console configuration option 'log-out-on-disconnect' In Juniper Networks Junos OS Evolved fails to log out an active CLI session when the console cable is disconnected. This could allow a malicious attacker with physical access to the console the ability to resume a previous interactive session and possibly gain administrative privileges. This issue affects all Juniper Networks Junos OS Evolved versions after 18.4R1-EVO, prior to 20.2R1-EVO.
Which versions are affected by CVE-2020-1666?
It affects 1 product.
Products include Juniper Junos Os Evolved.
How do I fix CVE-2020-1666?
No fix has been published for CVE-2020-1666 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-2020-1666 being exploited?
There is no known exploitation of CVE-2020-1666 in the wild and no public exploit code.
Other vulnerabilities in Juniper Junos Os Evolved
- CVE-2026-21902 Junos OS Evolved: PTX Series: A vulnerability allows a unauthenticated, network-based attacker to execute code as root
- CVE-2023-28983 Junos OS Evolved: Shell Injection vulnerability in the gNOI server
- CVE-2025-21599 Denial of service in Junos OS Evolved
- CVE-2024-47502 Junos OS Evolved: TCP session state is not always cleared on the Routing Engine leading to DoS
- CVE-2024-39531 Junos OS Evolved: ACX 7000 Series: Protocol specific DDoS configuration affects other protocols
Sources
Also known as GHSA-62gf-43c6-cfmp.