Echo: HTTPS Redirect and HSTS Bypass via Unconditional Trust of Forwarded Scheme Headers
CVE-2026-118657
Description Context.Scheme() unconditionally trusts four client-controlled HTTP headers to determine the request scheme, with no mechanism to configure trusted sources. This allows a remote unauthenticated attacker to bypass HTTPS redirect enforcement and suppress HSTS headers. The trusted headers (checked in this order of precedence): 1. X-Forwarded-Proto 2. X-Forwarded-Protocol 3. X-Forwarded-Ssl 4. X-Url-Scheme Threat model Scenario A — Directly exposed application (vulnerable by default): The Echo application listens on HTTP and is reachable directly by clients (no L7 proxy in front), or an attacker can bypass the proxy and reach the backend directly. In this case, the attacker has full control over all request headers. Sending X-Forwarded-Proto: https defeats the HTTPSRedirect middleware entirely — traffic stays on plaintext HTTP, enabling man-in-the-middle attacks. This is the primary scenario. The application is vulnerable by default with no misconfiguration required — simply using e.Pre(middleware.HTTPSRedirect()) as documented is sufficient. Scenario B — Behind L7 proxy with header sanitization (reduced risk): If the application is strictly behind a correctly configured…
Assessment
- CVSS
- 5.9 (v3.1)
- Severity
- Medium
- EPSS
- 0.00133% chance of exploitation in the next 30 days
- Known exploited
- Not listed in CISA KEV
- Exploit availability
- Nothing found in Exploit-DB, Metasploit, Nuclei or public PoC repositories
- Published
- 28 October 2026
- Last updated
- 28 October 2026
- Affected
- go · github.com/labstack/echo/v5, github.com/labstack/echo/v4
- Weakness
- CWE-346
CVSS vectorCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:L/A:N
At the source
References
- https://github.com/labstack/echo/security/advisories/GHSA-2ffq-g2xg-c22p
- https://github.com/labstack/echo/commit/b838391e2eade87ae7e5a09d7bb5087bec271ec1
- https://github.com/labstack/echo/commit/fc410094b2f3415cf2bf5204082137b205bfd5af
- https://github.com/labstack/echo/releases/tag/v4.16.0
- https://github.com/labstack/echo/releases/tag/v5.4.0
- https://github.com/advisories/GHSA-2ffq-g2xg-c22p
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