Incident Response Checklist for Suspected Axios Multipart Header Injection
CVE-2026-42037 creates a narrow injection path inside Axios multipart bodies. An incident response team should separate three questions: was an affected Axios version deployed, did untrusted Blob metadata reach it, and did a downstream parser act on an injected header? Affirmative answers at each stage matter more than a package alert by itself.
The advisory covers Axios versions from 1.0.0 through releases before 1.15.1. The defect is CWE-93 and has CVSS 3.1 5.3. The advisory includes a proof of concept, while CISA enrichment records exploitation as poc and automatable as no. This review found no KEV listing or verified active exploitation.
Preserve the relevant evidence
Identify upload routes that forward Blob or File-like values through Axios FormData. Collect request metadata for those routes within the applicable retention window: timestamp, route, authentication state, source address, declared MIME type, filename, downstream service, response status, and parser error. Avoid collecting file contents unless policy and legal review allow it.
Capture the deployed package version, image digest, and service build time for each route. Save the multipart boundary and part-header representation when available. A proxy log that records only the outer HTTP headers may not show the injected part line, so include receiver-side parser logs and application-side serialization diagnostics where they exist.
Test the deployment, not a random host
Reproduce the behavior in a controlled environment with the deployed Axios version. Use a synthetic Blob-like value and a local receiver. Confirm whether CR and LF survive into the part header. Then repeat with Axios 1.15.1 or later and with the application's validation layer enabled.
Do not send crafted multipart requests to third parties or production systems as an incident test. The goal is to confirm the service's own version and code path. A test against a local receiver gives enough evidence to distinguish a vulnerable build from a patched one without creating external side effects.
Correlate downstream impact
The advisory mentions possible bypass of Content-Type based filters, parser confusion, and phantom form fields. Search receiver logs for unexpected part headers, malformed multipart requests, and a mismatch between the original upload type and the type that influenced a file policy.
For each signal, determine what the downstream service did. Was the request rejected, stored, routed to another processor, or used to decide access? A parser error without a successful action has different meaning from a request that bypassed an intended filter and reached a privileged processor.
Do not describe every malformed request as exploitation. Attacker control, vulnerable code, a parser action, and a consequential outcome form the evidence chain. Preserve negative findings as clearly as positive ones.
Contain and remediate
Upgrade Axios to 1.15.1 or later and rebuild the affected artifacts. The release notes identify CRLF stripping in multipart headers, and pull request #10758 documents removal of CR and LF from Blob.type, default handling, and filename encoding.
If immediate deployment is impossible, reject CR and LF in MIME values and filenames at the upload boundary. Replace client metadata with an allowlisted internal type when the service has a known format set. Add receiver-side validation instead of trusting part metadata for a security decision.
Rotate credentials only if evidence shows data or request integrity was affected. The advisory's CVSS metrics list low integrity impact and no confidentiality or availability impact, but a downstream parser or application could change the consequence. Base containment on the actual affected path, not the score alone.
Close the investigation
Document the affected services, deployed versions, reachable routes, logs reviewed, downstream outcomes, and remediation artifacts. Confirm the production version after deployment. Add a regression test for CR, LF, and CRLF in Blob type and retain a test for a valid MIME value.
A useful final check asks whether a new malformed request would now be rejected or neutralized before entering multipart syntax. If that answer is only theoretical, the incident record should say so. If telemetry shows a downstream action, preserve the evidence and continue impact analysis.
Exposure context
ZoomEye Search app="Node.js" returned 5,548,145 fingerprint matches. The exact CVE Filter returned 0. These values do not identify affected Axios applications or confirm an incident. They only describe a broad Node.js fingerprint set and absent CVE indexing.
