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GHSA-x84c-p2g9-rqv9
No affected components available
In 26.0.0 and 26.0.1, IPv6 is not disabled on network interfaces, including those belonging to networks where --ipv6=false.
Impact
A container with an ipvlan or macvlan interface will normally be configured to share an external network link with the host machine. Because of this direct access, with IPv6 enabled:
- Containers may be able to communicate with other hosts on the local network over link-local IPv6 addresses.
- If router advertisements are being broadcast over the local network, containers may get SLAAC-assigned addresses.
- The interface will be a member of IPv6 multicast groups.
This means interfaces in IPv4-only networks present an unexpectedly and unnecessarily increased attack surface.
A container with an unexpected IPv6 address can do anything a container configured with an IPv6 address can do. That is, listen for connections on its IPv6 address, open connections to other nodes on the network over IPv6, or attempt a DoS attack by flooding packets from its IPv6 address. This has CVSS score AV:L/AC:H/PR:N/UI:R/S:C/C:N/I:N/A:L (2.7).
Because the container may not be constrained by an IPv6 firewall, there is increased potential for data exfiltration from the container. This has CVSS score AV:L/AC:H/PR:N/UI:R/S:U/C:H/I:N/A:N (4.7).
A remote attacker could send malicious Router Advertisements to divert traffic to itself, a black-hole, or another device. The same attack is possible today for IPv4 macvlan/ipvlan endpoints with ARP spoofing, TLS is commonly used by Internet APIs to mitigate this risk. The presence of an IPv6 route could impact the container's availability by indirectly abusing the behaviour of software which behaves poorly in a dual-stack environment. For example, it could resolve a name to a DNS AAAA record and keep trying to connect over IPv6 without ever falling back to IPv4, potentially denying service to the container. This has CVSS score AV:A/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H (4.5).
Patches
The issue is patched in 26.0.2.
Workarounds
To completely disable IPv6 in a container, use --sysctl=net.ipv6.conf.all.disable_ipv6=1 in the docker create or docker run command. Or, in the service configuration of a compose file, the equivalent:
sysctls:
- net.ipv6.conf.all.disable_ipv6=1
References
- sysctl configuration using
docker run:- https://docs.docker.com/reference/cli/docker/container/run/#sysctl
- sysctl configuration using
docker compose:- https://docs.docker.com/compose/compose-file/compose-file-v3/#sysctls
The vulnerability requires local access to the device to be exploited. It is difficult for an attacker to exploit this vulnerability and may require special conditions. An attacker does not need any special privileges or access rights. The attacker needs the user to perform some action, like clicking a link. The impact is confined to the system where the vulnerability exists. There is a high impact on the confidentiality of the information.
Exploitation attempts have been detected. Elevated vigilance and prompt remediation are advised.
The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.
We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.
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