{"cve":"CVE-2020-11091","nvd":{"published":"2020-06-03T23:15:11.167","modified":"2026-06-17T02:49:01.917","status":"Modified","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.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:C/C:N/I:H/A:N","score":5.8},"cwes":["CWE-350"],"references":["https://github.com/weaveworks/weave/commit/15f21f1899060f7716c70a8555a084e836f39a60","https://github.com/weaveworks/weave/security/advisories/GHSA-59qg-grp7-5r73","https://github.com/weaveworks/weave/commit/15f21f1899060f7716c70a8555a084e836f39a60","https://github.com/weaveworks/weave/security/advisories/GHSA-59qg-grp7-5r73"],"products":["weave:weave_net"],"source":"nvd","synced_at":"2026-10-19T21:05:42.039641217+00:00"},"epss":{"cve":"CVE-2020-11091","score":0.0086,"percentile":0.58523,"date":"2026-10-31"},"kev":null,"osv":[{"id":"GHSA-59qg-grp7-5r73","url":"https://osv.dev/vulnerability/GHSA-59qg-grp7-5r73","summary":"Weave Net clusters susceptible to MitM attacks via IPv6 rogue router advertisements","modified":"2026-07-08T05:59:40.255304971Z","packages":[{"ecosystem":"Go","name":"github.com/weaveworks/weave","purl":"pkg:golang/github.com/weaveworks/weave","ranges":["<2.6.3"],"fixed":["2.6.3"]}]},{"id":"GO-2022-0794","url":"https://osv.dev/vulnerability/GO-2022-0794","summary":"Weave Net clusters susceptible to MitM attacks via IPv6 rogue router advertisements in github.com/weaveworks/weave","modified":"2026-03-03T04:52:14.867062Z","packages":[{"ecosystem":"Go","name":"github.com/weaveworks/weave","purl":"pkg:golang/github.com/weaveworks/weave","ranges":["<2.6.3+incompatible"],"fixed":["2.6.3+incompatible"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}