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Medium, CVSS 6.9amended

Axios: Fetch Adapter Header Injection via Inherited FormData getHeaders

CVE-2026-101900GHSA-4hqw-qxg8-jxx2

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (axios 1.20.0), redeploy, then verify what is actually installed.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

Affected packages

  • npm axios

    Affected
    >= 1.12.0, < 1.20.0
    Fixed in
    1.20.0

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS 4.0
6.9 · CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:L/SI:H/SA:N · score source
EPSS
  • CVE-2026-101900: 0.55% estimated exploitation activity in the next 30 days; percentile 45.85 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.
Source description

As published by the source; long descriptions are shortened.

Summary Axios contains a guard in the Node HTTP adapter to avoid using an inherited Object.prototype.getHeaders as a FormData header source. The fetch adapter calls the shared resolveConfig() helper before dispatch, and that helper lacks the same guard. If another vulnerability pollutes Object.prototype with FormData-like properties and getHeaders(), the fetch adapter can merge attacker-controlled headers into the outbound request. Axios does not create the prototype pollution source. This is a read-side gadget in the fetch adapter configuration path. Impact An attacker with a prior same-process prototype-pollution primitive can inject headers into fetch-adapter requests. Depending on the target service, this may affect authorization, metadata-service access, cache behavior, conditional request handling, or other application-specific header logic. Plain objects are blocked by current FormData detection. The confirmed path uses arrays or non-plain class instances whose prototype chain…

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 4 · amended ·

    Amended from ghsa record GHSA-4hqw-qxg8-jxx2

  2. Revision 3 · amended ·

    Reviewed OSV alias/range/CVSS4 correction; package source scopes and original publication preserved. No customer finding resolved.

  3. Revision 2 · amended ·

    Amended from osv record GHSA-4hqw-qxg8-jxx2

  4. Revision 1 · created ·

    Published from ghsa record GHSA-4hqw-qxg8-jxx2

Agent brief

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# Patch Next advisory brief: CVE-2026-101900

Advisory: Axios: Fetch Adapter Header Injection via Inherited FormData getHeaders
IDs: CVE-2026-101900, GHSA-4hqw-qxg8-jxx2
Record: https://patchnext.com/advisories/cve-2026-101900 (revision 4, source checked 26 Oct 2026, 13:06 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 6.9)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: axios 1.20.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm axios: affected >= 1.12.0, < 1.20.0; fixed in 1.20.0

## Suggested inspection (read-only)
- `npm ls axios --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on axios.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-4hqw-qxg8-jxx2 (GitHub-reviewed advisory GHSA-4hqw-qxg8-jxx2 lists affected ranges: npm axios >=1.12.0 <1.20.0)
- Verified: https://osv.dev/vulnerability/GHSA-4hqw-qxg8-jxx2 (OSV record GHSA-4hqw-qxg8-jxx2 lists affected ranges: npm axios >=1.12.0 <1.20.0 (fixed))

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