Package Instance

Information Exposure in RunC
RunC allowed additional container processes via 'runc exec' to be ptraced by the pid 1 of the container.  This allows the main processes of the container, if running as root, to gain access to file-descriptors of these new processes during the initialization and can lead to container escapes or modification of runC state before the process is fully placed inside the container.

Moby's external DNS requests from 'internal' networks could lead to data exfiltration
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](https://datatracker.ietf.org/doc/html/rfc1918) 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.
-  PR <https://github.com/moby/moby/pull/46609> was opened in public to fix this issue, as it was not originally considered to have a security implication.
- [The official documentation](https://docs.docker.com/network/drivers/ipvlan/#:~:text=If%20the%20parent,the%20network%20completely) 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.

Privilege Escalation in Docker
Docker 1.0.0 uses world-readable and world-writable permissions on the management socket, which allows local users to gain privileges via unspecified vectors.

Path Traversal in Moby builder
util/binfmt_misc/check.go in Builder in Docker Engine before 19.03.9 calls os.OpenFile with a potentially unsafe qemu-check temporary pathname, constructed with an empty first argument in an ioutil.TempDir call.

`docker cp` allows unexpected chmod of host files in Moby Docker Engine
## Impact
A bug was found in Moby (Docker Engine) where attempting to copy files using `docker cp` into a specially-crafted container can result in Unix file permission changes for existing files in the host’s filesystem, widening access to others. This bug does not directly allow files to be read, modified, or executed without an additional cooperating process.

## Patches
This bug has been fixed in Moby (Docker Engine) 20.10.9. Users should update to this version as soon as possible. Running containers do not need to be restarted.

## Workarounds
Ensure you only run trusted containers.

## Credits
The Moby project would like to thank Lei Wang and Ruizhi Xiao for responsibly disclosing this issue in accordance with the [Moby security policy](https://github.com/moby/moby/blob/master/SECURITY.md).

## For more information
If you have any questions or comments about this advisory:

* [Open an issue](https://github.com/moby/moby/issues/new)
* Email us at  security@docker.com  if you think you’ve found a security bug

Authz zero length regression
A security vulnerability has been detected in certain versions of Docker Engine, which could allow an attacker to bypass [authorization plugins (AuthZ)](https://docs.docker.com/engine/extend/plugins_authorization/) under specific circumstances. The base likelihood of this being exploited is low. This advisory outlines the issue, identifies the affected versions, and provides remediation steps for impacted users.

### Impact

Using a specially-crafted API request, an Engine API client could make the daemon forward the request or response to an [authorization plugin](https://docs.docker.com/engine/extend/plugins_authorization/) without the body. In certain circumstances, the authorization plugin may allow a request which it would have otherwise denied if the body had been forwarded to it.


A security issue was discovered In 2018,  where an attacker could bypass AuthZ plugins using a specially crafted API request. This could lead to unauthorized actions, including privilege escalation. Although this issue was fixed in Docker Engine [v18.09.1](https://docs.docker.com/engine/release-notes/18.09/#security-fixes-1) in January 2019, the fix was not carried forward to later major versions, resulting in a regression. Anyone who depends on authorization plugins that introspect the request and/or response body to make access control decisions is potentially impacted.

Docker EE v19.03.x and all versions of Mirantis Container Runtime **are not vulnerable.**

### Vulnerability details

- **AuthZ bypass and privilege escalation:** An attacker could exploit a bypass using an API request with Content-Length set to 0, causing the Docker daemon to forward the request without the body to the AuthZ plugin, which might approve the request incorrectly.
- **Initial fix:** The issue was fixed in Docker Engine [v18.09.1](https://docs.docker.com/engine/release-notes/18.09/#security-fixes-1) January 2019..
- **Regression:** The fix was not included in Docker Engine v19.03 or newer versions. This was identified in April 2024 and patches were released for the affected versions on July 23, 2024. The issue was assigned [CVE-2024-41110](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2024-41110).

### Patches

- docker-ce v27.1.1 containes patches to fix the vulnerability.
- Patches have also been merged into the master, 19.0, 20.0, 23.0, 24.0, 25.0, 26.0, and 26.1 release branches.

### Remediation steps

- If you are running an affected version, update to the most recent patched version.
- Mitigation if unable to update immediately:
    - Avoid using AuthZ plugins.
    - Restrict access to the Docker API to trusted parties, following the principle of least privilege.


### References

- https://github.com/moby/moby/commit/fc274cd2ff4cf3b48c91697fb327dd1fb95588fb
- https://github.com/moby/moby/commit/a79fabbfe84117696a19671f4aa88b82d0f64fc1
- https://www.docker.com/blog/docker-security-advisory-docker-engine-authz-plugin/