Vulnerability · Published Apr 24, 2026 · Assigned by GitHub_M

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

Low 3.7

In plain English

A low-severity security flaw in axios from axios. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 12% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)3.7Low

Exploit odds (30 days)0.2%top 87.8% of all CVEs

Exploited in the wildNo reportsCISA SSVC: poc

Attack toolingNoneno public tooling known

Official 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.

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
Debian:12	node-axios	no fix listed	DEBIAN-CVE-2026-42040
Debian:13	node-axios	no fix listed	DEBIAN-CVE-2026-42040
Debian:14	node-axios	1.15.2-1	DEBIAN-CVE-2026-42040
Ubuntu:25.10	node-axios	no fix listed	UBUNTU-CVE-2026-42040
Ubuntu:26.10	node-axios	no fix listed	UBUNTU-CVE-2026-42040
npm	axios	0.31.1	GHSA-xhjh-pmcv-23jw
npm	axios	1.15.1	GHSA-xhjh-pmcv-23jw

Affected products (as reported)

Vendor	Product	Versions
axios	axios	>= 1.0.0, < 1.15.1< 0.31.1

Weakness: CWE-116, CWE-626 · Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N

References

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