Traffic interception via incorrect HSTS protocol check
Published Jul 8, 2026 · Updated Jul 8, 2026
Transport protection failure in GoFiber Fiber before 3.4.0 allows man-in-the-middle attackers to intercept or alter downgraded HTTP traffic. The helmet middleware compares c.Protocol(), which returns an HTTP version, with "https" instead of checking c.Scheme(), so configured HSTS headers are never emitted. Exploitation requires Helmet with HSTSMaxAge above zero, HTTPS service, and an attacker on the network path; affected traffic loses HSTS downgrade protection.
Summary
What happened
Transport protection failure in GoFiber Fiber before 3.4.0 allows man-in-the-middle attackers to intercept or alter downgraded HTTP traffic. The helmet middleware compares c.Protocol(), which returns an HTTP version, with "https" instead of checking c.Scheme(), so configured HSTS headers are never emitted. Exploitation requires Helmet with HSTSMaxAge above zero, HTTPS service, and an attacker on the network path; affected traffic loses HSTS downgrade protection.
The record
- CVE
- CVE-2026-53624
- Published
- Jul 8, 2026
- Updated
- Jul 8, 2026
- Vendor
- GoFiber
- Product
- Fiber
- Classifications
- CWE-319, T1557
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jul 8, 2026CVE publishedPublication date reported by the CVE source.
- Jul 8, 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.
- Affected versionversion=< 3.4.0
What conditions does exploitation require?
What is affected?
Published CVSS scores
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.
Weakness, pattern, technique
Public exploit references
- GHSA HSTS regression proof of conceptproof of concept · demonstrated
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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