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

Quick assessment

Affected
axios axios
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Axios是Axios开源的一款基于Promise（异步编程的一种解决方案）的HTTP客户端。 Axios 1.15.1之前版本和0.31.1之前版本存在安全漏洞，该漏洞源于encode函数中的字符映射将安全百分号编码的空字节反转回原始空字节。

CVSS 3.7 · Low EPSS 0.22% · P12

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application
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I. Basic Information for CVE-2026-42040

Vulnerability Information
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Vulnerability Title
Axios: Null Byte Injection via Reverse-Encoding in AxiosURLSearchParams
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
对输出编码和转义不恰当
Source: CVE Program / CVE List V5
Vulnerability Title
Axios 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Axios是Axios开源的一款基于Promise（异步编程的一种解决方案）的HTTP客户端。 Axios 1.15.1之前版本和0.31.1之前版本存在安全漏洞，该漏洞源于encode函数中的字符映射将安全百分号编码的空字节反转回原始空字节。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
axios axios >= 1.0.0, < 1.15.1 -

II. Public POCs for CVE-2026-42040

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III. Intelligence Information for CVE-2026-42040

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Vendor Advisories for CVE-2026-42040 (1)

Same Patch Batch · axios · 2026-04-24 · 12 CVEs total

CVE-2026-42033 7.4 HIGH Axios: Prototype Pollution Gadgets - Response Tampering, Data Exfiltration, and Request Hi
CVE-2026-42035 7.4 HIGH Axios: Header Injection via Prototype Pollution
CVE-2026-42043 7.2 HIGH Axios: Incomplete Fix for CVE-2025-62718 — NO_PROXY Protection Bypassed via RFC 1122 Loop
CVE-2026-42039 6.9 MEDIUM Axios: unbounded recursion in toFormData causes DoS via deeply nested request data
CVE-2026-42038 6.8 MEDIUM Axios: no_proxy bypass via IP alias allows SSRF
CVE-2026-42044 6.5 MEDIUM Axios: Invisible JSON Response Tampering via Prototype Pollution Gadget in `parseReviver`
CVE-2026-42042 5.4 MEDIUM Axios: XSRF Token Cross-Origin Leakage via Prototype Pollution Gadget in `withXSRFToken` B
CVE-2026-42037 5.3 MEDIUM Axios: CRLF Injection in multipart/form-data body via unsanitized blob.type in formDataToS
CVE-2026-42034 5.3 MEDIUM Axios: HTTP adapter streamed uploads bypass maxBodyLength when maxRedirects: 0
CVE-2026-42036 5.3 MEDIUM Axios: HTTP adapter streamed responses bypass maxContentLength
CVE-2026-42041 4.8 MEDIUM Axios: Authentication Bypass via Prototype Pollution Gadget in `validateStatus` Merge Stra

IV. Related Vulnerabilities

Same product: axios
Same vendor: axios
Same weakness: CWE-116