CVE-2026-42040
Axios: Null Byte Injection via Reverse-Encoding in AxiosURLSearchParams
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.
How to fix CVE-2026-42040
To remediate CVE-2026-42040, upgrade the affected package to a fixed version below.
- —no fix listed
- —upgrade to 1.15.1 or later
Is CVE-2026-42040 being exploited?
Low — EPSS is 0.1%, meaning exploitation activity has not been observed at scale.
Affected packages (2)
- from 0
- >= 1.0.0, < 1.15.1
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 3.1 | LOW3.7 | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N |