Answer Brief
AWS Security Blog advises setting a one-day dependency cooldown for npm and pip on Amazon Linux 2023 to block malicious packages published within the last 24 hours, citing recent supply chain events detected and removed within hours but still installed by users during the exposure window.
Signal Timeline
A quick visual path for analysts before reading the full brief.
- 1
Nx s1ngularity supply chain event with 4–5 hour exposure window
- 2
axios supply chain event with 2–3 hour exposure window
- 3
Bitwarden CLI supply chain event with 93-minute exposure window
- 4
TanStack supply chain event with 30-minute exposure window
Executive Summary: AWS Security Blog advises setting a one-day dependency cooldown for npm and pip on Amazon Linux 2023 to block malicious packages published within the last 24 hours, citing recent supply chain events detected and removed within hours but still installed by users during the exposure window.
Why It Matters
The AWS Security Blog post highlights a critical timing gap in open source package consumption: the period immediately after a package is published to registries like npm and PyPI, when automated scanners have not yet analyzed it for malicious content. During this window, threat actors can publish compromised packages that appear legitimate but contain harmful code. Although security teams often detect and remove these packages within hours—sometimes as fast as 30 minutes—users or automated systems may have already installed them, creating a real exposure window. The blog cites Datadog’s 2026 State of DevSecOps report, which found that 54% of JavaScript applications install at least one dependency within a day of its release, underscoring how widespread this risky behavior is. Recent incidents illustrate the speed and severity of the threat. Events involving packages like Nx s1ngularity (August 2025), axios (March 2026), Bitwarden CLI (April 2026), TanStack (May 2026), and node-ipc (May 2026) all had exposure windows ranging from 93 minutes to less than 24 hours. Notably, several of these malicious packages passed standard integrity checks such as provenance attestations and build verification, proving that cryptographic signing alone is insufficient to prevent supply chain compromise. This reinforces the need for temporal controls like cooldowns that operate independently of trust-based mechanisms. The proposed solution is straightforward: configure npm and pip to ignore versions published in the last 24 hours using the min-release-age and uploaded-prior-to settings. This gives security researchers and automated scanning tools time to analyze, flag, and remove malicious packages before they reach end users. Importantly, the cooldown does not affect lockfile-based installations (e.g., npm ci or pip install -r requirements.txt), preserving reproducibility for controlled environments while only impacting resolution of new or updated packages. AWS emphasizes that this approach balances two opposing risks: the danger of running outdated software with unpatched vulnerabilities versus the risk of adopting newly released packages that may contain undetected threats. By delaying adoption of the latest versions by just one day, organizations can significantly reduce supply chain exposure without sacrificing the ability to apply urgent security fixes. Override mechanisms allow teams to bypass the cooldown when needed—for example, when auditing tools like npm audit or pip_audit identify a known vulnerability requiring immediate patching. The blog notes growing industry adoption of cooldown features. As of May 2026, pnpm 11 enables minimumReleaseAge by default, making it opt-out rather than opt-in. Renovate has included a 3-day npm cooldown in its best-practices preset since 2025, widely used in enterprise environments. StepSecurity’s Secure Registry offers configurable cooldown periods for customers, with a recommended 10-day default. These trends indicate a shift toward temporal safety controls as a standard layer in software supply chain defense. AWS also details its own contributions to open source security, including Amazon Inspector’s AI-assisted scanning of upstream registries, which in 2025 identified over 150,000 unexpected npm packages tied to a token farming campaign. The company’s $12.5M grant to the Open Source Security Foundation funds proactive scanning infrastructure that benefits the broader ecosystem. These efforts complement user-side defenses like the cooldown by reducing the volume of malicious packages reaching registries in the first place. For Amazon Linux 2023 users, implementing the cooldown requires minimal setup: creating a global configuration directory and setting one-line configurations via npm-24 config or python3.14 -m pip config. The settings are backward-safe—older pip versions silently ignore the uploaded-prior-to flag—allowing gradual deployment. AWS concludes that this simple configuration provides immediate protection against most instances of unexpected code in npm and PyPI environments, while still enabling timely responses to legitimate security risks.
Event Type: security
Importance: high
Affected Companies
- Amazon Web Services
- Datadog
Affected Sectors
- DevSecOps
- cloud security
- software supply chain
Key Numbers
- Percentage of JavaScript apps installing dependencies within one day of release: 54%
- Detection window for recent malicious npm and PyPI packages: 30 minutes to less than 24 hours
- Unexpected npm packages linked to token farming campaign identified by Amazon Inspector in 2025: over 150,000
Timeline
- Nx s1ngularity supply chain event with 4–5 hour exposure window
- axios supply chain event with 2–3 hour exposure window
- Bitwarden CLI supply chain event with 93-minute exposure window
- TanStack supply chain event with 30-minute exposure window
- node-ipc supply chain event with less than 24-hour exposure window
- Amazon Linux 2023 release including Node.js 24 and Python 3.14 with cooldown support
- Industry adoption: pnpm 11 ships with minimumReleaseAge enabled by default; Renovate includes 3-day npm cooldown; StepSecurity offers configurable cooldown
- Publication date of AWS Security Blog post
Frequently Asked Questions
What is a dependency cooldown and how does it protect against supply chain attacks?
A dependency cooldown configures package managers like npm and pip to skip versions published within a set time window (e.g., 24 hours), blocking installation of newly released packages until security scanners have time to detect and remove malicious ones. It works by package age, not trust, and complements provenance checks.
How can users still apply urgent security fixes while using a package cooldown?
Users can override the cooldown on a per-command basis using flags like –min-release-age=0 for npm or –uploaded-prior-to="P0D" for pip. This allows installation of the latest version of specific packages needing urgent patches, while the cooldown remains active for all other installations.
Why does AWS recommend a 1-day cooldown specifically for Amazon Linux 2023 users?
Amazon Linux 2023 includes Node.js 24 (npm 11.10.0+) and Python 3.14 (pip 26.1+), both of which support native cooldown features. AWS recommends the 1-day cooldown because recent supply chain events were detected and removed within hours, but still installed by users during that window—making a 24-hour delay effective at blocking exposure.