CVE-2026-42040 LOW

CVE-2026-42040: Axios: Null Byte Injection via Reverse-Encoding in AxiosURLSearchParams

Vendor Axios
Product axios
Weakness CWE-116
Published April 24, 2026
Last update April 27, 2026
View on NVD All CVEs

CVSS base score

3.7/10
Attack vector Network
Attack complexity High
Privileges required None
User interaction None
Confidentiality None
Integrity Low

CVSS vector

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N

What the vulnerability does

01Description

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.

Key dates

02Disclosure timeline

April 24, 2026 CVE published
April 27, 2026 Record updated