Axios up to 1.19.x FormData ResolveConfig prototype pollution

Summaryinfo

A vulnerability was found in Axios up to 1.19.x. It has been declared as critical. This affects the function ResolveConfig of the component FormData. Such manipulation leads to prototype pollution. This vulnerability is documented as CVE-2026-101900. The attack can be executed remotely. There is not any exploit available. It is recommended to upgrade the affected component.

Detailsinfo

A vulnerability was found in Axios up to 1.19.x and classified as critical. Affected by this issue is the function ResolveConfig of the component FormData. The manipulation with an unknown input leads to a prototype pollution vulnerability. Using CWE to declare the problem leads to CWE-1321. The product receives input from an upstream component that specifies attributes that are to be initialized or updated in an object, but it does not properly control modifications of attributes of the object prototype. Impacted is confidentiality, integrity, and availability. CVE summarizes:

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.

The advisory is shared for download at github.com. This vulnerability is handled as CVE-2026-101900 since 09/28/2026. The exploitation is known to be easy. The attack may be launched remotely. No form of authentication is required for exploitation. There are known technical details, but no exploit is available. The MITRE ATT&CK project declares the attack technique as T1059.

Upgrading to version 1.20.0 eliminates this vulnerability.

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Productinfo

Name

• Axios

Version

• 1.0
• 1.1
• 1.2
• 1.3
• 1.4
• 1.5
• 1.6
• 1.7
• 1.8
• 1.9
• 1.10
• 1.11
• 1.12
• 1.13
• 1.14
• 1.15
• 1.16
• 1.17
• 1.18
• 1.19

Website

• Product: https://github.com/axios/axios/

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