GitHub Actions Runner Env Var Injection (pre-2.296.2) via Docker CLI
CVE-2022-39321 Published on October 25, 2022
GitHub Actions Runner vulnerable to Docker Command Escaping
GitHub Actions Runner is the application that runs a job from a GitHub Actions workflow. The actions runner invokes the docker cli directly in order to run job containers, service containers, or container actions. A bug in the logic for how the environment is encoded into these docker commands was discovered in versions prior to 2.296.2, 2.293.1, 2.289.4, 2.285.2, and 2.283.4 that allows an input to escape the environment variable and modify that docker command invocation directly. Jobs that use container actions, job containers, or service containers alongside untrusted user inputs in environment variables may be vulnerable. The Actions Runner has been patched, both on `github.com` and hotfixes for GHES and GHAE customers in versions 2.296.2, 2.293.1, 2.289.4, 2.285.2, and 2.283.4. GHES and GHAE customers may want to patch their instance in order to have their runners automatically upgrade to these new runner versions. As a workaround, users may consider removing any container actions, job containers, or service containers from their jobs until they are able to upgrade their runner versions.
Vulnerability Analysis
CVE-2022-39321 can be exploited with network access, and requires small amount of user privileges. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to be very high.
Weakness Type
What is a Shell injection Vulnerability?
The software constructs all or part of an OS command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended OS command when it is sent to a downstream component.
CVE-2022-39321 has been classified to as a Shell injection vulnerability or weakness.
Products Associated with CVE-2022-39321
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Affected Versions
actions runner:- Version < 2.283.4 is affected.
- Version >= 2.284.0, < 2.285.2 is affected.
- Version >= 2.286.0, < 2.289.4 is affected.
- Version >= 2.290.0, < 2.293.1 is affected.
- Version >= 2.294.0, < 2.296.2 is affected.
Exploit Probability
EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.