How severe is CVE-2026-45099?

No CVSS score has been assigned to CVE-2026-45099 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by CVE-2026-45099?

CVE-2026-45099 affects the following packages: github.com/gruntwork-io/terragrunt (Go). Ecosystems affected: Go.

How do I fix CVE-2026-45099?

Update github.com/gruntwork-io/terragrunt to 1.0.4 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-45099 is resolved across your whole dependency graph.

How do I detect CVE-2026-45099 in my Go dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/gruntwork-io/terragrunt, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2026-45099 if there is no patch (or I can't update yet)?

Resolve every user-supplied path to its canonical form and reject anything that escapes the intended directory, and run the component under an account that has no read or write access outside the directory it legitimately serves.

Is CVE-2026-45099 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-45099 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2026-45099?

CVE-2026-45099 has an EPSS (Exploit Prediction Scoring System) score of 0.5%, placing it in the 43th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2026-45099?

CVE-2026-45099 is classified as Path Traversal (CWE-22). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation. This is a high-impact weakness class that often enables remote code execution or data exposure.

When was CVE-2026-45099 published, and has it been updated?

CVE-2026-45099 was published on August 21, 2026 and was last updated on September 29, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐹 Go

Not in CISA KEV

CVE-2026-45099 — terragrunt

Fix: gruntwork-io/terragrunt@3d6f10d

CVE-2026-45099 is a Path Traversal vulnerability in github.com/gruntwork-io/terragrunt. A fix is available for github.com/gruntwork-io/terragrunt — see the affected versions and patch details below.

Terragrunt: Arbitrary File Deletion via Malicious Module Manifest

Also known asGHSA-8394-6f8r-whxgGO-2026-6241

Published

Aug 21, 2026

Updated

Sep 29, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Sep 30, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-45099.

EPSS Exploitation Probability

via FIRST.org ↗

0.5%probability of exploitation in next 30 days

Lower Risk+0.12%

Lower risk than most CVEs43th percentile — riskier than 43% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

Real-World Exposure

1 pkg affected

🐹github.com/gruntwork-io/terragrunt

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.

Description

Summary

Terragrunt is vulnerable to an arbitrary file deletion flaw when downloading external modules. If a remote module contains a maliciously crafted .terragrunt-module-manifest file, Terragrunt can be tricked into deleting files anywhere on the local filesystem that the Terragrunt process has access to.

Impact

This vulnerability impacts users who download and run untrusted or compromised OpenTofu/Terraform modules. The file deletion occurs during the module download and initialization phase, meaning it happens before OpenTofu or Terraform executes.

In a CI/CD environment or automated runner, an attacker-controlled module could delete arbitrary files, causing denial of service in the deployment pipeline. In a local environment, it could lead to the loss of local source code or configuration files.

This vulnerability is a deletion-only primitive; it does not directly allow for arbitrary code execution (RCE) or data exfiltration.

Affected Versions

Terragrunt < v1.0.4

Patches

This vulnerability has been resolved in Terragrunt version v1.0.4.

All users are strongly advised to upgrade.

Workarounds

If users cannot upgrade immediately, they can mitigate this risk by:

Strictly auditing the source URLs of all remote modules used in their Terragrunt configurations.
Only consuming modules from trusted, internally vetted sources or verified registries.
Pinning module versions to specific, known-safe Git commit SHAs rather than mutable tags or branches.

Technical Details

Terragrunt tracks files copied into a downloaded module's working directory using a .terragrunt-module-manifest file. During the directory cleanup process, Terragrunt decodes the entries in this manifest and removes the listed files to prepare a fresh directory for OpenTofu/Terraform runs.

Previously, Terragrunt trusted the manifest provided by the downloaded module without verifying that the paths scheduled for deletion remained within the boundaries of the module's destination directory. An attacker could forge a manifest containing directory traversal paths, causing the cleanup function to target files outside the cache. The patch introduces a secure boundary check to ensure all cleaned paths remain safely isolated inside the intended manifest folder.

Credit

Terragrunt would like to thank Francesco Sabiu (@fsabiu) for discovering and responsibly disclosing this vulnerability.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐹Go	`github.com/gruntwork-io/terragrunt`	all versions	1.0.4`go get github.com/gruntwork-io/terragrunt@v1.0.4`

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/gruntwork-io/terragrunt, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update github.com/gruntwork-io/terragrunt to 1.0.4 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-45099 is resolved across your whole dependency graph.
Workarounds
Resolve every user-supplied path to its canonical form and reject anything that escapes the intended directory, and run the component under an account that has no read or write access outside the directory it legitimately serves.

Frequently Asked Questions

### Summary Terragrunt is vulnerable to an arbitrary file deletion flaw when downloading external modules. If a remote module contains a maliciously crafted `.terragrunt-module-manifest` file, Terragrunt can be tricked into deleting files anywhere on the local filesystem that the Terragrunt process has access to. ### Impact This vulnerability impacts users who download and run untrusted or compromised OpenTofu/Terraform modules. The file deletion occurs during the module download and initialization phase, meaning it happens before OpenTofu or Terraform executes. In a CI/CD environment or a

O3 Security · Impact-Aware SCA

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