Package Instance

BuildKit vulnerable to possible host system access from mount stub cleaner
### Impact
A malicious BuildKit frontend or Dockerfile using `RUN --mount` could trick the feature that removes empty files created for the mountpoints into removing a file outside the container, from the host system.

### Patches
The issue has been fixed in v0.12.5

### Workarounds
Avoid using BuildKit frontend from an untrusted source or building an untrusted Dockerfile containing `RUN --mount` feature.

### References

BuildKit vulnerable to possible race condition with accessing subpaths from cache mounts
### Impact
Two malicious build steps running in parallel sharing the same cache mounts with subpaths could cause a race condition that can lead to files from the host system being accessible to the build container.

### Patches
The issue has been fixed in v0.12.5

### Workarounds
Avoid using BuildKit frontend from an untrusted source or building an untrusted Dockerfile containing cache mounts with `--mount=type=cache,source=...` options.

### References
https://www.openwall.com/lists/oss-security/2019/05/28/1

Buildkit's interactive containers API does not validate entitlements check
### Impact
In addition to running containers as build steps, BuildKit also provides APIs for running interactive containers based on built images. It was possible to use these APIs to ask BuildKit to run a container with elevated privileges. Normally, running such containers is only allowed if special `security.insecure` entitlement is enabled both by buildkitd configuration and allowed by the user initializing the build request.

### Patches
The issue has been fixed in v0.12.5 .

### Workarounds
Avoid using BuildKit frontends from untrusted sources. A frontend image is usually specified as the `#syntax` line on your Dockerfile, or with `--frontend` flag when using `buildctl build` command.

### References

BuildKit vulnerable to possible panic when incorrect parameters sent from frontend
### Impact
A malicious BuildKit client or frontend could craft a request that could lead to BuildKit daemon crashing with a panic.

### Patches
The issue has been fixed in v0.12.5

### Workarounds
Avoid using BuildKit frontends from untrusted sources. A frontend image is usually specified as the `#syntax` line on your Dockerfile, or with `--frontend` flag when using `buildctl build` command. 

### References

Classic builder cache poisoning
The classic builder cache system is prone to cache poisoning if the image is built `FROM scratch`.
Also, changes to some instructions (most important being `HEALTHCHECK` and `ONBUILD`) would not cause a cache miss.


An attacker with the knowledge of the Dockerfile someone is using could poison their cache by making them pull a specially crafted image that would be considered as a valid cache candidate for some build steps.

For example, an attacker could create an image that is considered as a valid cache candidate for:
```
FROM scratch
MAINTAINER Pawel
```

when in fact the malicious image used as a cache would be an image built from a different Dockerfile.

In the second case, the attacker could for example substitute a different `HEALTCHECK` command.


### Impact

23.0+ users are only affected if they explicitly opted out of Buildkit (`DOCKER_BUILDKIT=0` environment variable) or are using the `/build` API endpoint (which uses the classic builder by default).

All users on versions older than 23.0 could be impacted. An example could be a CI with a shared cache, or just a regular Docker user pulling a malicious image due to misspelling/typosquatting.

Image build API endpoint (`/build`) and `ImageBuild` function from `github.com/docker/docker/client` is also affected as it the uses classic builder by default. 


### Patches

Patches are included in Moby releases:

- v25.0.2
- v24.0.9
- v23.0.10

### Workarounds

- Use `--no-cache` or use Buildkit if possible (`DOCKER_BUILDKIT=1`, it's default on 23.0+ assuming that the buildx plugin is installed).
- Use `Version = types.BuilderBuildKit` or `NoCache = true` in `ImageBuildOptions` for `ImageBuild` call.