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High, CVSS 7.5amended

Axios is Vulnerable to Denial of Service via __proto__ Key in mergeConfig

CVE-2026-25639GHSA-43fc-jf86-j433

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (axios 1.13.5, 0.30.3), 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.

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Affected packages

  • npm axios

    Affected
    >= 1.0.0, <= 1.13.4<= 0.30.2
    Fixed in
    0.30.3, 1.13.5

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS
7.5 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
EPSS
  • CVE-2026-25639: 2.80% estimated exploitation activity in the next 30 days; percentile 86.48 (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.

Denial of Service via proto Key in mergeConfig Summary The mergeConfig function in axios crashes with a TypeError when processing configuration objects containing proto as an own property. An attacker can trigger this by providing a malicious configuration object created via JSON.parse(), causing complete denial of service. Details The vulnerability exists in lib/core/mergeConfig.js at lines 98-101: When prop is 'proto': 1. JSON.parse('{"proto": {...}}') creates an object with proto as an own enumerable property 2. Object.keys() includes 'proto' in the iteration 3. mergeMap['proto'] performs prototype chain lookup, returning Object.prototype (truthy object) 4. The expression mergeMap[prop] || mergeDeepProperties evaluates to Object.prototype 5. Object.prototype(...) throws TypeError: merge is not a function The mergeConfig function is called by: - Axios.request() at lib/core/Axios.js:75 - Axios.getUri() at lib/core/Axios.js:201 - All HTTP method shortcuts (get, post, etc.) at…

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 2 · amended ·

    Amended from ghsa record GHSA-43fc-jf86-j433

  2. Revision 1 · created ·

    Published from osv record GHSA-43fc-jf86-j433

Agent brief

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# Patch Next advisory brief: CVE-2026-25639

Advisory: Axios is Vulnerable to Denial of Service via __proto__ Key in mergeConfig
IDs: CVE-2026-25639, GHSA-43fc-jf86-j433
Record: https://patchnext.com/advisories/cve-2026-25639 (revision 2, source checked 26 Oct 2026, 12:51 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: axios 1.13.5, 0.30.3. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm axios: affected >= 1.0.0, <= 1.13.4; <= 0.30.2; fixed in 0.30.3, 1.13.5

## 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://osv.dev/vulnerability/GHSA-43fc-jf86-j433 (OSV record GHSA-43fc-jf86-j433 lists affected ranges: npm axios >=1.0.0 =0 <0.30.3 (fixed))
- Verified: https://github.com/advisories/GHSA-43fc-jf86-j433 (GitHub-reviewed advisory GHSA-43fc-jf86-j433 lists affected ranges: npm axios >=1.0.0 =0 <=0.30.2)

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