CVE-2026-42040Public exploitNetwork attack vector

Request URL manipulation via reversed null encoding

Published Apr 24, 2026 · Updated Apr 24, 2026

Null byte injection in Axios before 0.31.1 and 1.0.0 through 1.15.0 allows remote attackers to place raw null bytes in request URLs. The encode() function in lib/helpers/AxiosURLSearchParams.js converts encodeURIComponent output %00 back into a raw null byte. Exploitation requires direct AxiosURLSearchParams.toString() use or a custom serializer that delegates to the internal encoder; a downstream parser can then truncate URLs, bypass filters, or corrupt logs.

CVSS severity3.7
Low
EPSS probability0.22%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Null byte injection in Axios before 0.31.1 and 1.0.0 through 1.15.0 allows remote attackers to place raw null bytes in request URLs. The encode() function in lib/helpers/AxiosURLSearchParams.js converts encodeURIComponent output %00 back into a raw null byte. Exploitation requires direct AxiosURLSearchParams.toString() use or a custom serializer that delegates to the internal encoder; a downstream parser can then truncate URLs, bypass filters, or corrupt logs.

The record

CVE
CVE-2026-42040
Published
Apr 24, 2026
Updated
Apr 24, 2026
Vendor
Axios
Product
Axios
Classifications
CWE-626, CWE-116
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 24, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 24, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 0.31.1
  2. Affected versionversion=>= 1.0.0, < 1.15.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Axios · Axiosversion=< 0.31.1; version=>= 1.0.0, < 1.15.1

Published CVSS scores

3.7GitHub, Inc.CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

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

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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