What’s Vulnerable › Vulnerabilities

CVE-2026-105766: Chainguard Academy (edu) Nginx directory redirect downgrades HTTPS requests to HTTP

• Severity: low (CVSS 3.1 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.1% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-10-05 · updated 2026-10-06
• Weakness: CWE-319

Description

Use of the backend-facing $scheme variable in the trailing-slash directory redirect in nginx.conf of Chainguard Academy (edu) from commit 0b75ff98057f69b044a3e7194e428066ac5ad0d4 before commit 93dc0e50739c225f5aee2e803800a47fc0feb906 allows an on-path network attacker to read or modify documentation content served to a victim via an HTTPS request for a slashless directory path, because TLS terminates at the load balancer in front of Nginx and the resulting 301 response redirects the client to a plaintext http:// URL. Browsers that ship the HSTS preload list are not affected, because the .dev top-level domain is preloaded; clients that do not enforce HSTS, such as command-line HTTP clients and scripts that follow redirects, are affected.

References

• https://github.com/chainguard-dev/edu/commit/93dc0e50739c225f5aee2e803800a47fc0feb906
• https://github.com/chainguard-dev/edu/pull/3989

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