Instituto Nacional de ciberseguridad. Sección Incibe
Instituto Nacional de Ciberseguridad. Sección INCIBE-CERT

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CVE-2026-21697

Severity CVSS v4.0:
HIGH
Type:
CWE-362 Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')
Publication date:
07/01/2026
Last modified:
08/01/2026

Description

axios4go is a Go HTTP client library. Prior to version 0.6.4, a race condition vulnerability exists in the shared HTTP client configuration. The global `defaultClient` is mutated during request execution without synchronization, directly modifying the shared `http.Client`'s `Transport`, `Timeout`, and `CheckRedirect` properties. Impacted applications include that that use axios4go with concurrent requests (multiple goroutines, `GetAsync`, `PostAsync`, etc.), those where different requests use different proxy configurations, and those that handle sensitive data (authentication credentials, tokens, API keys). Version 0.6.4 fixes this issue.

Impact

Vector 4.0
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N CVSS v4.0 Severity and Metrics:

Base Score: 8.20 HIGH
Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N

Attack Vector (AV): Network
Attack Complexity (AC): Low
Attack Requirements (AT): Present
Privileges Required (PR): None
User Interaction (UI): None
Confidentiality (VC): None
Integrity (VI): High
Availability (VA): None
Confidentiality (SC): None
Integrity (SI): None
Availability (SA): None

Base Score 4.0
8.20
Severity 4.0
HIGH

References to Advisories, Solutions, and Tools