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

Exp

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.

Published: 2026-04-24 Last update: 2026-06-17 Assigner: [email protected] Source: [email protected]

Conclusion & alert: CVE-2026-42040 is rated Exploit Available (50/100): CVSS Low severity, with low exploitation likelihood (EPSS 0.20%). Core evidence: 1 public exploit reference(s) are indexed (Exploit-DB). Mandatory action: Public exploits are available—assess exposure, apply mitigations, and prioritize patching.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Public exploit references (Exploit-DB) for CVE-2026-42040

EDB-ID Source Kind Published Link
nvd_ref exploit_tag Exploit-DB ↗

Exploit prediction scoring system (EPSS) score for CVE-2026-42040

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.06% 0.20% +0.15%
2 2026-05-13 0.03% 0.06% +0.03%
3 2026-04-25 0.03%

Full EPSS history (3 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-42040

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
3.7 3.1 LOW
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:L)
Attackers could change some data, but it’s limited—not everything goes.
Availability (A:N)
Service keeps running; no real outage angle.
2.2 1.4 [email protected]

Weakness enumeration for CVE-2026-42040

GitHub Security Advisory for CVE-2026-42040

GHSA-xhjh-pmcv-23jw · Severity: low · Ecosystem: npm — Axios: Null Byte Injection via Reverse-Encoding in AxiosURLSearchParams

OS Trackers for CVE-2026-42040

vendor priority summary link
debian not yet assigned CVE-2026-42040 not yet assigned priority: Debian including 1 source packages (node-axios), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): open 3, resolved 2. https://security-tracker.debian.org/tracker/CVE-2026-42040
suse medium CVE-2026-42040 severity moderate: SUSE including 27 source package names (corepack22, corepack24, …), 118 product×package rows across 20 product lines (SUSE Linux Enterprise High Performance Computing 15 SP4-LTSS, SUSE Linux Enterprise High Performance Computing 15 SP5-LTSS, … (20 product lines)): Known Not Affected 118. https://www.suse.com/security/cve/CVE-2026-42040/
ubuntu medium CVE-2026-42040 medium priority: Ubuntu including 1 source packages (node-axios), 6 status rows across 6 suites (focal, jammy, noble, questing, resolute, upstream): needs-triage 5, released 1. https://ubuntu.com/security/CVE-2026-42040

Affected software / configurations for CVE-2026-42040

Vendor Product Version Raw CPE
axios axios < 0.31.1 cpe:2.3:a:axios:axios:*:*:*:*:*:node.js:*:*
axios axios >= 1.0.0, < 1.15.1 cpe:2.3:a:axios:axios:*:*:*:*:*:node.js:*:*

References for CVE-2026-42040

cvelogic Threat Intelligence