CVE-2026-53624 in Fiber
Summary
by MITRE • 07/08/2026
Fiber is an Express inspired web framework written in Go. Prior to 3.4.0, the helmet middleware in middleware/helmet/helmet.go never sets the Strict-Transport-Security response header even when HSTSMaxAge is configured because it checks c.Protocol() for https instead of c.Scheme(). This issue is fixed in version 3.4.0.
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Analysis
by VulDB Data Team • 07/08/2026
The vulnerability in question affects Fiber web framework versions prior to 3.4.0, specifically within the helmet middleware component that implements security headers for HTTP responses. This represents a critical configuration error that undermines the intended security posture of applications using this framework. The issue stems from an incorrect conditional check within the middleware implementation where the code evaluates c.Protocol() instead of c.Scheme() when determining whether to apply the Strict-Transport-Security header.
The technical flaw manifests as a logic error in the helmet middleware's HSTS enforcement mechanism. When developers configure HSTSMaxAge parameter to enable HTTP Strict Transport Security, the middleware should automatically inject the Strict-Transport-Security response header into all HTTPS responses. However, due to the incorrect protocol checking mechanism, the middleware fails to recognize when requests are actually served over HTTPS, resulting in the security header never being applied regardless of configuration settings. This vulnerability directly contradicts the intended functionality of the helmet middleware and creates a false sense of security for applications that rely on this component.
The operational impact of this vulnerability is significant as it leaves applications exposed to man-in-the-middle attacks and downgrade attacks that could compromise user sessions and sensitive data transfers. Without proper HSTS enforcement, attackers can potentially force browsers to communicate over unencrypted HTTP connections even when the application is configured to prefer HTTPS. This weakness undermines the security layer that should protect against protocol downgrade attacks as defined by the CWE-319 category, which specifically addresses the transmission of information over insecure channels. The vulnerability essentially neutralizes one of the primary defenses against certain classes of web application attacks that are catalogued under the ATT&CK framework's T1071.004 technique for Application Layer Protocol: DNS.
The fix implemented in version 3.4.0 corrects the fundamental logic error by switching from c.Protocol() to c.Scheme() method calls, ensuring proper detection of HTTPS protocol usage. This change aligns with standard web application security practices and ensures that when developers configure HSTS parameters, those configurations are properly enforced. Organizations using affected versions should prioritize immediate upgrade to version 3.4.0 or later to remediate this vulnerability. The resolution addresses the core issue by ensuring proper protocol detection while maintaining all other helmet middleware functionality, thereby restoring the intended security posture for applications that depend on Fiber's security headers implementation.
This vulnerability demonstrates the critical importance of thorough testing and validation of security mechanisms within web frameworks. It highlights how seemingly minor implementation errors in security components can completely negate the intended protection, emphasizing the need for comprehensive security reviews and proper adherence to established security standards such as those defined by OWASP and NIST guidelines for secure web application development. The incident underscores the necessity of robust testing procedures that validate security header implementations specifically under various protocol scenarios to prevent such configuration-related vulnerabilities from reaching production environments.