CVE-2025-59331 — is-arrayish
CVE-2025-59331 is a CWE-506 vulnerability in is-arrayish. A fix is available for is-arrayish — see the affected versions and patch details below.
[email protected] contains malware after npm account takeover
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-2025-59331.
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.
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.
is-arrayishnpmDescription
Impact
On 8 September 2025, an npm publishing account for is-arrayish was taken over after a phishing attack. Version 0.3.3 was published, functionally identical to the previous patch version, but with a malware payload added attempting to redirect cryptocurrency transactions to the attacker's own addresses from within browser environments.
Local environments, server environments, command line applications, etc. are not affected. If the package was used in a browser context (e.g. a direct <script> inclusion, or via a bundling tool such as Babel, Rollup, Vite, Next.js, etc.) there is a chance the malware still exists and such bundles will need to be rebuilt.
The malware seemingly only targets cryptocurrency transactions and wallets such as MetaMask. See references below for more information on the payload.
Patches
npm removed the offending package from the registry over the course of the day on 8 September, preventing further downloads from npm proper.
On 13 September, the package owner published new patch versions to help cache-bust those using private registries who might still have the compromised version cached. This version is functionally identical to the previously known-good version, published as a patch version bump above the compromised version.
Users should update to the latest patch version, completely remove their node_modules directory, clean their package manager's global cache, and rebuild any browser bundles from scratch.
Those operating private registries or registry mirrors should purge the offending versions from any caches.
References
- https://www.aikido.dev/blog/npm-debug-and-chalk-packages-compromised
- https://socket.dev/blog/npm-author-qix-compromised-in-major-supply-chain-attack
- https://www.ox.security/blog/npm-packages-compromised/
Point of Contact
In the event suspicious behavior is still observed for the package listed in this security advisory after performing all of the above cleaning operations (see Patches above), please reach out via one of the following channels of communication:
- Bluesky, compromised publishing account owner: https://bsky.app/profile/bad-at-computer.bsky.social
debugrepository, tracking issue (applies to all packages affected in the breach): https://github.com/debug-js/debug/issues/1005
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | is-arrayish | ≥ 0.3.3&&< 0.3.4 | 0.3.4npm install is-arrayish@0.3.4 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for is-arrayish, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update is-arrayish to 0.3.4 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2025-59331 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-2025-59331 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2025-59331. 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-2025-59331 in your dependencies?
O3 Security finds CVE-2025-59331 across npm dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.