CVE-2026-42040

Axios: Null Byte Injection via Reverse-Encoding in AxiosURLSearchParams

State: Published
Severity: 3.7 Low
Published: Apr 24, 2026
Updated: Apr 27, 2026
Reserved: Apr 23, 2026

Description

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.

Scores

CVSS	Score	Vector	Source
3.1	3.7 Low	CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N	GitHub_M

Weaknesses

CWE-116 Improper Encoding or Escaping of Output
CWE-626 Null Byte Interaction Error (Poison Null Byte)

Affected Products

Product	Versions
axiosaxios	>= 1.0.0, < 1.15.1Affected < 0.31.1Affected

References

https://github.com/axios/axios/security/advisories/GHSA-xhjh-pmcv-23jw

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