Axios up to 0.31.0/1.15.0 AxiosURLSearchParams.js encode escape output

Summaryinfo

A vulnerability was found in Axios up to 0.31.0/1.15.0 and classified as problematic. Impacted is the function encode in the library lib/helpers/AxiosURLSearchParams.js. The manipulation results in escape output. This vulnerability is identified as CVE-2026-42040. The attack can be executed remotely. There is not any exploit available. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability classified as problematic has been found in Axios up to 0.31.0/1.15.0. Affected is the function encode in the library lib/helpers/AxiosURLSearchParams.js. The manipulation with an unknown input leads to a escape output vulnerability. CWE is classifying the issue as CWE-116. The product prepares a structured message for communication with another component, but encoding or escaping of the data is either missing or done incorrectly. As a result, the intended structure of the message is not preserved. This is going to have an impact on integrity. CVE summarizes:

Axios is a promise based HTTP client for the browser and Node.js. Prior to 1.15.1 and 0.31.1, the encode() function in lib/helpers/AxiosURLSearchParams.js contains a character mapping (charMap) at line 21 that reverses the safe percent-encoding of null bytes. After encodeURIComponent('\x00') correctly produces the safe sequence %00, the charMap entry '%00': '\x00' converts it back to a raw null byte. Primary impact is limited because the standard axios request flow is not affected. This vulnerability is fixed in 1.15.1 and 0.31.1.

The advisory is shared for download at github.com. This vulnerability is traded as CVE-2026-42040 since 04/23/2026. The exploitability is told to be difficult. It is possible to launch the attack remotely. The exploitation doesn't require any form of authentication. There are known technical details, but no exploit is available.

Upgrading to version 0.31.1 or 1.15.1 eliminates this vulnerability.

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Productinfo

Name

• Axios

Version

• 0.1
• 0.2
• 0.3
• 0.4
• 0.5
• 0.6
• 0.7
• 0.8
• 0.9
• 0.10
• 0.11
• 0.12
• 0.13
• 0.14
• 0.15
• 0.16
• 0.17
• 0.18
• 0.19
• 0.20
• 0.21
• 0.22
• 0.23
• 0.24
• 0.25
• 0.26
• 0.27
• 0.28
• 0.29
• 0.30
• 0.31.0
• 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
• 1.15.0

Website

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

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