CVE-2026-105766

Chainguard Academy (edu) Nginx directory redirect downgrades HTTPS requests to HTTP

Published Oct 5, 2026 CVSS 4.0 · 2.3 Low EPSS < 1% KEV · Not listed
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.

Remediation

Vendor Solution

Fixed in commit 93dc0e50739c225f5aee2e803800a47fc0feb906, which hardcodes the https scheme in the redirect. The fix is deployed to edu.chainguard.dev; no user action is required.

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
First Time appeared Chainguard
Chainguard chainguard Academy (edu)
Vendors & Products Chainguard
Chainguard chainguard Academy (edu)
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
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.
Title Chainguard Academy (edu) Nginx directory redirect downgrades HTTPS requests to HTTP
Weaknesses CWE-319
References
Metrics cvssV3_1

{'score': 3.1, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:L/A:N'}

cvssV4_0

{'score': 2.3, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
chainguard
Published
Updated
Oct 6, 2026, 1:44 PM
Reserved
Oct 5, 2026, 7:21 PM
Status
Deferred
Published
Oct 5, 2026, 8:17 PM
Modified
Oct 6, 2026, 3:03 PM