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If your server (control-plane) nodes were not started with the --token CLI flag or config file key, a randomized token was generated during initial cluster startup. This key is used both for joining new nodes to the cluster, and for encrypting cluster bootstrap data within the datastore. Ensure that you retain a copy of this token, as is required when restoring from backup.
You may retrieve the token value from any server already joined to the cluster:
// UnaryServerInterceptor returns a grpc.UnaryServerInterceptor suitable
// for use in a grpc.NewServer call.
func UnaryServerInterceptor(opts ...Option) grpc.UnaryServerInterceptor {
out of the box adds labels
net.peer.sock.addr
net.peer.sock.port
that have unbound cardinality. It leads to the server's potential memory exhaustion when many malicious requests are sent.
Details
An attacker can easily flood the peer address and port for requests.
PoC
Apply the attached patch to the example and run the client multiple times. Observe how each request will create a unique histogram and how the memory consumption increases during it.
Impact
In order to be affected, the program has to configure a metrics pipeline, use UnaryServerInterceptor, and does not filter any client IP address and ports via middleware or proxies, etc.
Others
It is similar to already reported vulnerabilities.
An attacker may cause an HTTP/2 endpoint to read arbitrary amounts of header data by sending an excessive number of CONTINUATION frames. Maintaining HPACK state requires parsing and processing all HEADERS and CONTINUATION frames on a connection. When a request's headers exceed MaxHeaderBytes, no memory is allocated to store the excess headers, but they are still parsed. This permits an attacker to cause an HTTP/2 endpoint to read arbitrary amounts of header data, all associated with a request which is going to be rejected. These headers can include Huffman-encoded data which is significantly more expensive for the receiver to decode than for an attacker to send. The fix sets a limit on the amount of excess header frames we will process before closing a connection.
Moby is an open source container framework originally developed by Docker Inc. as Docker. It is a key component of Docker Engine, Docker Desktop, and other distributions of container tooling or runtimes. As a batteries-included container runtime, Moby comes with a built-in networking implementation that enables communication between containers, and between containers and external resources.
Moby's networking implementation allows for creating and using many networks, each with their own subnet and gateway. This feature is frequently referred to as custom networks, as each network can have a different driver, set of parameters, and thus behaviors. When creating a network, the --internal flag is used to designate a network as internal. The internal attribute in a docker-compose.yml file may also be used to mark a network internal, and other API clients may specify the internal parameter as well.
When containers with networking are created, they are assigned unique network interfaces and IP addresses (typically from a non-routable RFC 1918 subnet). The root network namespace (hereafter referred to as the 'host') serves as a router for non-internal networks, with a gateway IP that provides SNAT/DNAT to/from container IPs.
Containers on an internal network may communicate between each other, but are precluded from communicating with any networks the host has access to (LAN or WAN) as no default route is configured, and firewall rules are set up to drop all outgoing traffic. Communication with the gateway IP address (and thus appropriately configured host services) is possible, and the host may communicate with any container IP directly.
In addition to configuring the Linux kernel's various networking features to enable container networking, dockerd directly provides some services to container networks. Principal among these is serving as a resolver, enabling service discovery (looking up other containers on the network by name), and resolution of names from an upstream resolver.
When a DNS request for a name that does not correspond to a container is received, the request is forwarded to the configured upstream resolver (by default, the host's configured resolver). This request is made from the container network namespace: the level of access and routing of traffic is the same as if the request was made by the container itself.
As a consequence of this design, containers solely attached to internal network(s) will be unable to resolve names using the upstream resolver, as the container itself is unable to communicate with that nameserver. Only the names of containers also attached to the internal network are able to be resolved.
Many systems will run a local forwarding DNS resolver, typically present on a loopback address (127.0.0.0/8), such as systemd-resolved or dnsmasq. Common loopback address examples include 127.0.0.1 or 127.0.0.53. As the host and any containers have separate loopback devices, a consequence of the design described above is that containers are unable to resolve names from the host's configured resolver, as they cannot reach these addresses on the host loopback device.
To bridge this gap, and to allow containers to properly resolve names even when a local forwarding resolver is used on a loopback address, dockerd will detect this scenario and instead forward DNS requests from the host/root network namespace. The loopback resolver will then forward the requests to its configured upstream resolvers, as expected.
Impact
Because dockerd will forward DNS requests to the host loopback device, bypassing the container network namespace's normal routing semantics entirely, internal networks can unexpectedly forward DNS requests to an external nameserver.
By registering a domain for which they control the authoritative nameservers, an attacker could arrange for a compromised container to exfiltrate data by encoding it in DNS queries that will eventually be answered by their nameservers. For example, if the domain evil.example was registered, the authoritative nameserver(s) for that domain could (eventually and indirectly) receive a request for this-is-a-secret.evil.example.
Docker Desktop is not affected, as Docker Desktop always runs an internal resolver on a RFC 1918 address.
Patches
Moby releases 26.0.0-rc3, 25.0.5 (released) and 23.0.11 (to be released) are patched to prevent forwarding DNS requests from internal networks.
Workarounds
Run containers intended to be solely attached to internal networks with a custom upstream address (--dns argument to docker run, or API equivalent), which will force all upstream DNS queries to be resolved from the container network namespace.
Background
yair zak originally reported this issue to the Docker security team.
The official documentation claims that "the --internal flag that will completely isolate containers on a network from any communications external to that network," which necessitated this advisory and CVE.
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This PR contains the following updates:
1.29.3+rke2r1->1.29.4+rke2r1Warning
Some dependencies could not be looked up. Check the Dependency Dashboard for more information.
Release Notes
rancher/rke2 (rancher/rke2)
v1.29.4+rke2r1: v1.29.4+rke2r1Compare Source
This release updates Kubernetes to v1.29.4.
Important Note
If your server (control-plane) nodes were not started with the
--tokenCLI flag or config file key, a randomized token was generated during initial cluster startup. This key is used both for joining new nodes to the cluster, and for encrypting cluster bootstrap data within the datastore. Ensure that you retain a copy of this token, as is required when restoring from backup.You may retrieve the token value from any server already joined to the cluster:
Changes since v1.29.3+rke2r1:
rke2 certificate(#5750)Charts Versions
Packaged Component Versions
Available CNIs
Calico v3.27.3
Helpful Links
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v1.29.4-rc4+rke2r1: v1.29.4-rc4+rke2r1Compare Source
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v1.29.4-rc2+rke2r1: v1.29.4-rc2+rke2r1Compare Source
v1.29.4-rc1+rke2r1: v1.29.4-rc1+rke2r1Compare Source
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