Safeguard 2.6: Allowlist Authorized Libraries

To meet the safeguard 2.6: allowlist authorized libraries requirement, you must define which software libraries are approved for use and enforce that only those libraries can be introduced into production code and build pipelines. Operationalize it by combining a documented approval standard with automated controls in CI/CD, registries, and endpoint tooling, plus exception handling and evidence retention. ¹

Key takeaways:

• You need an approved-library standard plus technical enforcement in the developer workflow, not a policy-only list. ¹
• Scope includes open-source packages, internal shared libraries, and runtime-loaded modules across all supported languages. ²
• Auditors will ask for proof of enforcement (pipeline blocks, logs, tickets), not screenshots of a wiki page. ²

Allowlisting authorized libraries is a software supply chain control. You are drawing a clear boundary around which libraries engineering teams may use, then making that boundary real through build and deployment enforcement. CIS identifies this as Safeguard 2.6, and the practical intent is to reduce the chance that an unvetted library introduces known vulnerabilities, malicious code, licensing risk, or unexpected network and data behaviors. ¹

For a Compliance Officer, CCO, or GRC lead, the fastest path is to treat this like an operational control with an owner, triggers, execution steps, and exception rules. Your target state is simple: developers can move quickly using an approved catalog, and unapproved libraries are blocked (or require an explicit exception) before code reaches production. ²

This page gives requirement-level implementation guidance you can hand to engineering and security leads. It focuses on how to define the allowlist, enforce it in CI/CD and artifact repositories, create an exception process that does not become a loophole, and retain evidence that demonstrates the control actually runs. ²

Requirement summary (Safeguard 2.6)

Safeguard 2.6: Allowlist Authorized Libraries requires you to maintain a defined set of approved libraries and prevent or tightly control use of libraries outside that set. The operator goal is consistent: reduce the attack surface and supply chain exposure created by arbitrary dependency selection. ¹

Plain-English interpretation

• Maintain a single source of truth for approved libraries (by ecosystem, name, and version rules). ²
• Put guardrails in the places libraries enter your environment: dependency management, CI/CD builds, artifact/package registries, and endpoint software execution where relevant. ²
• Provide a documented pathway to request additions or exceptions with security review and a time-bounded decision. ²

Regulatory text

Excerpt (provided): “CIS Controls v8 safeguard 2.6 implementation expectation (Allowlist Authorized Libraries).” ²

What the operator must do: implement an allowlisting program for software libraries so that engineering teams use only authorized libraries, with governance (approval and exceptions) and technical controls that enforce the decision. Keep evidence that the allowlist exists, is maintained, and is enforced in the software delivery lifecycle. ¹

Who it applies to

This safeguard applies broadly to organizations building, deploying, or maintaining software, including enterprises, service organizations, and technology organizations. ²

Operational contexts where it matters most

• Software development teams using public package ecosystems (npm, PyPI, Maven/Gradle, NuGet, RubyGems, Go modules). ²
• Platform/DevOps teams operating CI/CD, build agents, artifact registries, and container pipelines where dependencies are resolved and packaged. ²
• Security teams owning software supply chain and vulnerability management who can define guardrails and monitor violations. ²
• Third parties contributing code (contractors, SIs) who can introduce libraries through pull requests or build scripts; your SDLC controls must cover them as well. ²

What you actually need to do (step-by-step)

1) Create the “control card” so ownership is unambiguous

Document a short control runbook (one page is fine) with: objective, in-scope systems, control owner, approvers, trigger events (new library request, new repo, new language), enforcement points, exception rules, and evidence locations. This closes the common audit gap where teams cannot show who runs the control or how it operates. ²

Minimum assignments that work in practice

• Control owner: AppSec or DevSecOps lead
• Approver(s): Security + Engineering platform owner, with Legal consulted for licensing-sensitive ecosystems
• Operators: CI/CD admins, artifact registry admins

2) Define what “library” means in your environment

Write a scope statement that includes:

• Direct dependencies declared in manifests (package.json, requirements.txt, pom.xml, etc.).
• Transitive dependencies (pulled automatically).
• Internally produced shared libraries.
• Runtime plugins/modules loaded post-build where applicable. ²

This definition prevents the classic loophole: “We allowlisted direct deps, but transitive deps brought in the real risk.”

3) Build the allowlist data model (what exactly is approved)

Your allowlist needs enough structure to be enforceable:

Recommended allowlist fields (practical minimum)

• Ecosystem/language (npm, PyPI, Maven, etc.)
• Package name (canonical)
• Allowed versions (exact versions or version ranges you explicitly accept)
• Source (public registry vs internal registry)
• Approval date, approver, justification
• Review trigger (new major version, CVE event, end-of-life)
• Notes on license constraints (if relevant) ²

Store it in a system that can drive automation (Git repo, CMDB-like tool, or security platform configuration). A spreadsheet can work temporarily, but it is harder to enforce and audit.

4) Decide your enforcement pattern (block vs gate vs monitor)

Pick one per environment and maturity:

Pattern	What happens	Where it fits	Audit posture
Block	Builds fail or installs are denied	High-risk apps, internet-facing services	Strongest evidence if logs retained
Gate	Requires approval/exception ticket to proceed	Mixed maturity orgs	Acceptable if approvals are consistent
Monitor	Detect and alert only	Early stage or legacy	Weakest; needs a roadmap to enforcement

CIS expects allowlisting as a safeguard; for most regulated environments, “monitor only” will draw follow-up questions because it does not actually prevent introduction. ²

5) Implement technical enforcement where libraries enter the pipeline

You want controls in at least two layers so a single misconfiguration does not bypass the intent.

Enforcement points to prioritize

• CI builds: policy checks that compare dependencies (including transitive) against the allowlist and fail builds or require a gate.
• Artifact/package registries: restrict which upstreams are reachable; prefer mirrored/proxied registries where you can control what enters.
• Developer workstations/build agents: prevent ad hoc installs that never pass through controlled build paths where feasible.
• Container builds: validate OS packages and language packages used in image layers. ²

Operational tip: Start with your “golden paths” (standard build templates) so the majority of repositories inherit enforcement with minimal repo-by-repo change management.

6) Set up the intake workflow for new libraries (and make it fast)

A slow approval path creates shadow dependencies. Create a standardized request with: package name, intended use, data access profile, network behavior expectations, license type (if known), maintenance signals (release cadence, maintainer), and alternatives. ²

Decision outputs

• Approved and added to allowlist (with version rule)
• Rejected with rationale and acceptable alternatives
• Approved via exception with constraints (scope, time-box, compensating controls)

7) Exceptions: treat them like risk acceptances with expiry

Define exception criteria and require: business owner, security reviewer, scope (repo/app), expiry condition, and required remediation (replace library, upgrade, or fork internally). Keep exceptions searchable and reportable. ²

8) Operate the control: health checks and remediation tracking

Run recurring checks that answer:

• Which repos used non-allowlisted libraries this period?
• Which exceptions are active and which are expired?
• Which allowlisted libraries now fail security criteria and need removal or version pin changes? ²

Track remediation items to validated closure with due dates and owners. Evidence of closure matters as much as detection. ²

Required evidence and artifacts to retain

Audits usually fail on “show me” gaps. Keep a minimum evidence bundle per operating cycle. ²

Evidence bundle (store in a consistent location)

1. Control card/runbook: owner, scope, triggers, enforcement points, exception rules. ²
2. Current allowlist export: machine-readable list with approval metadata. ²
3. Change history: pull requests/commits or tickets that show who approved new libraries and why. ²
4. Enforcement proof: CI/CD policy configuration, sample pipeline logs showing blocks/gates, registry restriction settings. ²
5. Exceptions register: active and closed exceptions with approvals and expiry conditions. ²
6. Control health check output: periodic reports plus remediation tickets to closure. ²

Common exam/audit questions and hangups

Expect these and prepare a canned evidence path.

• “Show me the authoritative list.” Provide the allowlist export plus change history. ²
• “How do you enforce this?” Walk through one build that fails on an unapproved library and show the log artifact. ²
• “How do you handle transitive dependencies?” Provide dependency tree evidence and the control mechanism that evaluates it. ²
• “What about emergencies?” Show the exception workflow and how you ensure follow-up replacement. ²
• “Who owns it?” Point to the control card, named owner, and operating cadence artifacts. ²

Frequent implementation mistakes (and how to avoid them)

1. Allowlist exists only as a document. Fix: tie it to CI/CD checks and registry controls so developers cannot bypass it. ²
2. No version strategy. Fix: define version rules; “approved package” without version constraints is not enforceable. ²
3. Exceptions become permanent. Fix: require an expiry condition and track exceptions like risk acceptances with follow-up work. ²
4. Only direct dependencies checked. Fix: evaluate transitive dependencies and container layers where libraries appear. ²
5. Evidence scattered across tools. Fix: define the minimum evidence bundle and a single retention location so production is repeatable. ²

Enforcement context and risk implications

No public enforcement cases were provided in the source catalog for this safeguard, so this page does not cite regulator actions. The risk case is still concrete: unauthorized libraries increase exposure to supply chain attacks, unplanned vulnerable components, and licensing conflicts that can force rework or service disruption. CIS positions this safeguard as a practical security control to reduce those paths. ¹

Practical execution plan (30/60/90-day)

Time-boxed milestones can be helpful, but the provided sources do not support numeric timelines. Use phased execution without day counts.

Phase 1 (Immediate): establish governance and the first enforceable boundary

• Publish the control card with an owner, approvers, and exception rules. ²
• Choose in-scope ecosystems (start with the most used language stacks). ²
• Stand up a first allowlist format and repository of record. ²
• Implement enforcement on one “golden path” pipeline or template and prove you can block or gate unapproved libraries with logs. ²

Phase 2 (Near-term): expand enforcement coverage and formalize intake

• Add the library request workflow and SLA expectations internally (no numbers needed; just make it predictable). ²
• Extend enforcement to additional CI pipelines and artifact registries. ²
• Create the exceptions register and reporting. ²

Phase 3 (Ongoing): operate, measure, and continuously tighten

• Run recurring control health checks and track remediation to closure. ²
• Review allowlisted libraries for continued authorization triggers (major upgrades, CVEs, deprecations). ²
• Reduce exception volume by improving developer experience (approved alternatives, internal mirrors). ²

Where Daydream fits (without changing your engineering toolchain)

Daydream can hold the control card, map the evidence bundle to each operating cycle, and keep remediation and exceptions tied to the requirement so you can answer audits with a single, consistent evidence trail. This matches the practical gap CIS programs often face: unclear ownership and missing proof of operation. ²

Frequently Asked Questions

Do we have to allowlist every single transitive dependency?

You need a control that evaluates transitive dependencies against your authorization rules, because transitive libraries are a common entry point for risk. In practice, many teams allowlist at the package and version-rule level and enforce via automated dependency resolution checks. ²

Can we start with “monitor only” and still claim compliance?

Monitoring can be a starting point, but auditors typically expect an allowlist to be enforced where dependencies enter builds and releases. If you start with monitoring, document the roadmap to blocking or gating and retain monitoring outputs as interim evidence. ²

How do we handle languages and ecosystems across many teams?

Define a baseline allowlist per ecosystem and let product teams request additions through a single intake workflow. Standard build templates and centralized registries reduce variance without requiring every team to become policy experts. ²

What evidence is strongest for auditors?

Machine-generated proof that enforcement occurred: pipeline logs showing a blocked build, registry logs showing denied pulls, plus the approval record that added an authorized library. Pair that with a current allowlist export and an exceptions register. ²

How should we treat internally developed shared libraries?

Treat them as libraries subject to authorization, versioning, and change control, especially if multiple applications consume them. Add them to the allowlist with ownership and release metadata so enforcement can distinguish approved internal packages from ad hoc builds. ²

What if a third party ships code that includes unapproved libraries?

Put the same CI/CD and repository controls on inbound code paths (pull requests, build runs, artifact ingestion) so third-party contributions cannot introduce dependencies outside your allowlist without review. Contract language helps, but technical enforcement closes the gap. ²

Footnotes

1. CIS Controls v8; CIS Controls Navigator v8

2. CIS Controls v8