CVE-2026-42089 is a high-severity (CVSS 8.6) CWE-829 vulnerability in yeoman-environment. A fix is available for yeoman-environment — see the affected versions and patch details below.
yeoman-environment Vulnerable to Arbitrary Package Installation without User Confirmation
Exploitation Status
No confirmed exploitation observed yet
- A successful exploit gives an attacker total control of the affected component, not partial access.
- 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-2026-42089.
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-2026-42089 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 379,145 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
How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.
yeoman-environmentnpmDescription
Impact
yeoman-environment versions >= 2.9.0 and < 6.0.1 install missing local generator packages from caller-supplied package names without user confirmation. In downstream consumers that pass attacker-controlled project configuration into this path, this can result in arbitrary package installation and code execution during CLI bootstrap.
The vulnerable method is installLocalGenerators(), which calls repository.install() directly without prompting the user.
Patches
Upgrade to yeoman-environment 6.0.1, which adds an interactive confirmation prompt before installation (PR #753).
Workarounds
None.
Resources
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | yeoman-environment | ≥ 2.9.0&&< 6.0.1 | 6.0.1npm install yeoman-environment@6.0.1 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for yeoman-environment, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update yeoman-environment to 6.0.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-42089 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-2026-42089 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2026-42089. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
This is an Important flaw in Yeoman Environment that could lead to arbitrary code execution. The vulnerability arises when downstream consumers process attacker-controlled project configurations, allowing the installation of unconfirmed local generator packages during CLI bootstrap. Exploitation requires user…
To mitigate this issue, users should avoid processing project configurations from untrusted sources with Yeoman Environment. Ensure that all project configurations and generator package names are from trusted origins to prevent the installation of arbitrary packages and subsequent code execution.Source: Red Hat security advisory for CVE-2026-42089 (CC BY 4.0)
Frequently Asked Questions
Is CVE-2026-42089 in your dependencies?
O3 Security finds CVE-2026-42089 across npm dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.