Is CVE-2020-11091 actively exploited?

No active exploitation of CVE-2020-11091 has been confirmed so far. Continue monitoring, as exploit status can change.

Can CVE-2020-11091 be exploited remotely?

Yes. CVE-2020-11091 is exploitable remotely over the network (CVSS attack vector: Network).

What is the CVSS score of CVE-2020-11091?

CVE-2020-11091 has a CVSS score of 5.8 (MEDIUM).

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MEDIUM

CVE-2020-11091

CWE-350Published: June 3, 2020· Updated: Jun 17, 2026

5.8

CVSS v3.1

Official Description

In Weave Net before version 2.6.3, an attacker able to run a process as root in a container is able to respond to DNS requests from the host and thereby insert themselves as a fake service. In a cluster with an IPv4 internal network, if IPv6 is not totally disabled on the host (via ipv6.disable=1 on the kernel cmdline), it will be either unconfigured or configured on some interfaces, but it's pretty likely that ipv6 forwarding is disabled, ie /proc/sys/net/ipv6/conf//forwarding == 0. Also by default, /proc/sys/net/ipv6/conf//accept_ra == 1. The combination of these 2 sysctls means that the host accepts router advertisements and configure the IPv6 stack using them. By sending rogue router advertisements, an attacker can reconfigure the host to redirect part or all of the IPv6 traffic of the host to the attacker controlled container. Even if there was no IPv6 traffic before, if the DNS returns A (IPv4) and AAAA (IPv6) records, many HTTP libraries will try to connect via IPv6 first then fallback to IPv4, giving an opportunity to the attacker to respond. If by chance you also have on the host a vulnerability like last year's RCE in apt (CVE-2019-3462), you can now escalate to the host. Weave Net version 2.6.3 disables the accept_ra option on the veth devices that it creates.

NVD Source

Technical Analysis

CVE-2020-11091 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

Exploitation requires high privileges, which limits the exposure to scenarios where an attacker has already gained initial access.

A successful exploit results in full integrity compromise (data manipulation), with a CVSS base score of 5.8.

The vulnerability has a "Changed" scope, meaning successful exploitation can impact components beyond the vulnerable component itself — such as the host operating system or adjacent services.