CVE-2026-42040CWE-116CWE-626

Axios: Null Byte Injection via Reverse-Encoding in AxiosURLSearchParams

Low · published April 24, 2026

CVSS v3.1
3.7
EPSS
0%
Percentile
17.3
In the wild
Unconfirmed
What it is

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 record
Technical detail
CVSS v3.1
3.7 · LOW
Vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N
CVSS v4.0
Not supplied
EPSS
0.00264 · 17.3th percentile
Weaknesses
CWE-116 · Improper Encoding or Escaping of Output; CWE-626 · Null Byte Interaction Error (Poison Null Byte)
Published
2026-04-24T17:40Z
EPSS history
Timeline
  • 24 APR 17:40Z
    Axios: Null Byte Injection via Reverse-Encoding in AxiosURLSearchParams
    cvelistv5