CVE-2025-23206 — aws-cdk-lib
Fix: aws/aws-cdk@3e4f377CVE-2025-23206 is a CWE-347 vulnerability in aws-cdk-lib. A fix is available for aws-cdk-lib — see the affected versions and patch details below.
IAM OIDC custom resource allows connection to unauthorized OIDC provider in aws-cdk
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-2025-23206.
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.
aws-cdk-libnpmDescription
Impact
Users who use IAM OIDC custom resource provider package will download CA Thumbprints as part of the custom resource workflow, https://github.com/aws/aws-cdk/blob/d16482fc8a4a3e1f62751f481b770c09034df7d2/packages/%40aws-cdk/custom-resource-handlers/lib/aws-iam/oidc-handler/external.ts#L34.
However, the current tls.connect method will always set rejectUnauthorized: false which is a potential security concern. CDK should follow the best practice and set rejectUnauthorized: true. However, this could be a breaking change for existing CDK applications and we should fix this with a feature flag.
Note that this is marked as low severity Security advisory because the issuer url is provided by CDK users who define the CDK application. If they insist on connecting to a unauthorized OIDC provider, CDK should not disallow this. Additionally, the code block is run in a Lambda environment which mitigate the MITM attack.
As a best practice, CDK should still fix this issue under a feature flag to avoid regression.
packages/@aws-cdk/custom-resource-handlers/lib/aws-iam/oidc-handler/external.ts
❯❱ problem-based-packs.insecure-transport.js-node.bypass-tls-verification.bypass-tls-verification
Checks for setting the environment variable NODE_TLS_REJECT_UNAUTHORIZED to 0, which disables TLS
verification. This should only be used for debugging purposes. Setting the option rejectUnauthorized
to false bypasses verification against the list of trusted CAs, which also leads to insecure
transport.
Patches
The patch is in progress. To mitigate, upgrade to CDK v2.177.0 (Expected release date 2025-02-22).
Once upgraded, please make sure the feature flag '@aws-cdk/aws-iam:oidcRejectUnauthorizedConnections' is set to true in cdk.context.json or cdk.json. More details on feature flag setting is here.
Workarounds
N/A
References
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | aws-cdk-lib | all versions | 2.177.0npm install aws-cdk-lib@2.177.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for aws-cdk-lib, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update aws-cdk-lib to 2.177.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2025-23206 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-2025-23206 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2025-23206. 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-2025-23206 in your dependencies?
O3 Security finds CVE-2025-23206 across npm dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.