CVE-2026-40090 is a high-severity (CVSS 7.1) Path Traversal vulnerability in github.com/zarf-dev/zarf. A fix is available for github.com/zarf-dev/zarf — see the affected versions and patch details below.
Zarf has a Path Traversal via Malicious Package Metadata.Name — Arbitrary File Write
Exploitation Status
No confirmed exploitation observed yet
- 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-2026-40090.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2026-40090 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 378,156 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
github.com/zarf-dev/zarfReal-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
Impact
This vulnerability impacts users of zarf package inspect sbom or zarf package inspect documentation on untrusted packages.
Patches
#4793, now fixed in version v0.74.2
Workarounds
Avoid inspecting unsigned packages
Description
The package inspect sbom and package inspect documentation subcommands construct output file paths by joining a user-controlled output directory with the package's Metadata.Name field, which is attacker-controlled data read from the package archive. The Metadata.Name field is validated against a regex on create, ^[a-z0-9][a-z0-9\-]*$, however a malicious user could unarchive a package to change the .Metadata.Name field and the files inside the SBOMS.tar. This would lead to arbitrary file write in a location of the attackers choosing.
Neither location sanitizes or validates the package name before using it in the file path.
SBOM inspection:
outputPath := filepath.Join(o.outputDir, pkgLayout.Pkg.Metadata.Name)
err = pkgLayout.GetSBOM(ctx, outputPath)
Documentation inspection (line 1219):
outputPath := filepath.Join(o.outputDir, fmt.Sprintf("%s-documentation", pkgLayout.Pkg.Metadata.Name))
return pkgLayout.GetDocumentation(ctx, outputPath, o.keys)
pkgLayout.Pkg.Metadata.Name is read directly from the untrusted package's zarf.yaml manifest. An attacker can craft a malicious Zarf package where Metadata.Name contains path traversal sequences or root paths such as ../../etc/cron.d/malicious or /home/user/.ssh/authorized_keys.
CVSS Explainations
Attack Vector
Verdict: Network
A malicious package could be published to OCI and inspected directly with zarf package inspect sbom oci://<bad-package>
Attack Complexity
Verdict: Low It is not complicated to make and publish a malicious package. The Attacker only needs to edit the zarf.yaml and sboms.tar then edit the checksums.
Privileges Required
Verdict: None
The attacker is relying on the runner of zarf package inspect sbom|documentation and needs no other privileges.
User Interaction
Verdict: Required The user must run the inspect command
Scope
Verdict: Unchanged The vulnerability operates entirely within the permissions of the user running zarf package inspect. The file write can't escape the privilege boundary of that user
Confidentiality
Verdict: None This is an arbitrary file write vulnerability. The attacker can place or overwrite files on the filesystem but the vulnerability does not provide any mechanism to read or exfiltrate data from the target system.
Integrity
Verdict: High The attacker controls both the file path (via Metadata.Name) and the file content (via the SBOM or documentation files inside the archive). This allows writing attacker-controlled content to arbitrary locations on the filesystem, limited only by the permissions of the user running the inspect command. Realistic exploitation includes writing SSH authorized_keys, cron jobs, or shell profiles.
Availability
Verdict: Low The vulnerability does not directly target service availability. However, an attacker could overwrite files that cause system disruption.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/zarf-dev/zarf | ≥ 0.23.0&&< 0.74.2 | 0.74.2go get github.com/zarf-dev/zarf@v0.74.2 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/zarf-dev/zarf, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update github.com/zarf-dev/zarf to 0.74.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-40090 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2026-40090 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2026-40090. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-40090 in your dependencies?
O3 Security finds CVE-2026-40090 across Go dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.