CVE-2026-21697 is a high-severity vulnerability affecting the rezmoss axios4go library, a Go HTTP client. This vulnerability allows a race condition in the shared HTTP client configuration. The global `defaultClient` is mutated during request execution without synchronization, modifying critical properties such as `Transport`, `Timeout`, and `CheckRedirect` within the shared `http.Client`. Applications utilizing axios4go with concurrent requests, those using various proxy configurations, or handling sensitive data are at risk.
The CVSS score for this vulnerability is 8.2, indicating a high severity that necessitates immediate attention. The potential for exploitation is significant, as attackers may leverage this flaw to compromise the integrity of applications handling sensitive information, including authentication credentials and API keys. Organizations should address this vulnerability in their patch cycles.
Version 0.6.4 addresses this issue, and organizations using earlier versions should prioritize upgrading to this release. The vulnerability was publicly disclosed on January 7, 2026, emphasizing the importance of prompt remediation.
Given the potential impact, organizations are urged to assess their use of axios4go and implement necessary updates. The risk to organizations includes compromised data integrity and potential unauthorized access.
For further details, refer to the official security advisory and release notes for version 0.6.4.
Vulnerability Details
The vulnerability is classified as a race condition (CWE-362), which occurs when multiple threads or processes access shared data and try to change it simultaneously. This can lead to unpredictable behavior in applications. In this case, the axios4go library's shared HTTP client configuration can be altered during request execution, causing integrity issues for applications relying on it.
The CVSS score of 8.2 signifies a high severity level. The attack vector is network-based, allowing remote exploitation with low attack complexity. No privileges are required for exploitation, and user interaction is not necessary.
Affected versions include all versions prior to 0.6.4, making it crucial for organizations to upgrade to the latest version to mitigate this vulnerability.
Technical Analysis
The root cause of CVE-2026-21697 lies in the improper synchronization of the shared HTTP client configuration. During concurrent execution of requests, modifications to the `defaultClient` are not managed correctly, leading to race conditions. This vulnerability can be exploited through various attack vectors, primarily over the network.
The attack complexity is classified as low, as no special conditions are necessary for an attacker to exploit this flaw. Additionally, the vulnerability requires no privileges, and user interaction is not needed, making it easier for malicious actors to take advantage of the situation.
The impacts of this vulnerability are significant. The integrity of sensitive data, including authentication credentials and API tokens, can be compromised. Conversely, confidentiality and availability impacts are rated as none, meaning the primary concern centers around integrity.
Risk & Impact Analysis
Risk to organizations includes the potential for data integrity compromise due to the race condition vulnerability. Applications that handle sensitive data and use concurrent requests are directly affected, increasing the blast radius for organizations using axios4go.
Given the high CVSS score of 8.2, organizations should prioritize remediation efforts in their patch cycles. The risk of exploitation is elevated, and organizations must remain vigilant to prevent unauthorized access and data breaches.
The urgency for patching is underscored by the potential for significant negative impacts on integrity and the associated risks to sensitive information.
Exploitation Status
Signal | Status |
|---|---|
Known Exploit | No |
Public PoC | No |
Actively Exploited | No |
Ransomware Use | No |
Affected Versions
The affected versions of axios4go include all versions prior to 0.6.4. Organizations utilizing this library should ensure they upgrade to this version to mitigate the identified vulnerability.
Mitigation & Remediation
To remediate the vulnerability, organizations should upgrade to axios4go version 0.6.4. If immediate patching is not possible, consider implementing workarounds, such as avoiding concurrent requests that modify the shared HTTP client configuration.
Configuration hardening and monitoring are also recommended to detect potential exploitation attempts. Regular audits of applications using axios4go can help identify vulnerabilities and ensure compliance with security best practices. For further information on penetration testing, organizations can explore our penetration testing services to assess their security posture.
Detection Guidance
Organizations should monitor logs for unusual patterns or anomalies related to axios4go usage. Pay attention to concurrent requests and any modifications to the shared HTTP client configuration. Implement network signatures to detect potential exploitation attempts and ensure that system changes are logged for review.
AppSecure Threat Intelligence Insight
The long-term significance of CVE-2026-21697 highlights the need for robust concurrency control mechanisms in shared libraries. This vulnerability represents a trend where race conditions can lead to severe integrity issues in applications. Organizations should develop strategies to mitigate these risks, including regular auditing of third-party libraries.
Security teams should focus on patterns of behavior that could indicate exploitation and improve their defenses against similar vulnerabilities. For a comprehensive understanding of security testing best practices, organizations can refer to our penetration testing methodology and consider adopting a continuous security testing approach.
Additionally, involvement in a vulnerability management program can enhance the security posture of the organization and help in addressing such vulnerabilities proactively.
Organizations should prioritize building a culture of security that emphasizes proactive measures, continuous learning, and adaptation to emerging threats.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
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