CVE-2026-118658

Echo has Arbitrary Scheme Injection in WWWRedirect/NonWWWRedirect Middlewares via X-Forwarded-Proto

GET /path HTTP/1.1
Host: example.com
X-Forwarded-Proto: javascript

Response:
HTTP/1.1 301 Moved Permanently
Location: javascript://www.example.com/path

• Open redirect to arbitrary scheme URLs when app is not behind a proxy that strips X-Forwarded-Proto
• Cache poisoning when behind a CDN that caches redirect responses keyed by path
• file:// scheme injection could trigger file access in some browser configurations

Untrusted input controls a URL used for redirection, which can forward users to attacker-controlled sites. Typical impact: phishing and credential harvesting via a trusted domain.

CVE-2026-118658 has a CVSS score of 4.7 (Medium). The vector is network-reachable, no privileges required, and user interaction required. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (5.1.1, 4.15.2); upgrading removes the vulnerable code path.

Kodem intelligence

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Whitelist scheme in c.Scheme() to only return http or https:

func (c *Context) Scheme() string {
    if c.IsTLS() {
        return "https"
    }
    if scheme := c.request.Header.Get(HeaderXForwardedProto); scheme != "" {
        scheme = strings.ToLower(strings.TrimSpace(scheme))
        if scheme == "https" {
            return "https"
        }
    }
    return "http"
}

1. What is CVE-2026-118658? CVE-2026-118658 is a medium-severity open redirect vulnerability in github.com/labstack/echo/v5 (go), affecting versions < 5.1.1. It is fixed in 5.1.1, 4.15.2. Untrusted input controls a URL used for redirection, which can forward users to attacker-controlled sites.
2. How severe is CVE-2026-118658? CVE-2026-118658 has a CVSS score of 4.7 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which packages are affected by CVE-2026-118658?
   • github.com/labstack/echo/v5 (go) (versions < 5.1.1)
   • github.com/labstack/echo/v4 (go) (versions < 4.15.2)
4. Is there a fix for CVE-2026-118658? Yes. CVE-2026-118658 is fixed in 5.1.1, 4.15.2. Upgrade to this version or later.
5. Is CVE-2026-118658 exploitable, and should I be worried? Whether CVE-2026-118658 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2026-118658 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2026-118658?
   • Upgrade github.com/labstack/echo/v5 to 5.1.1 or later
   • Upgrade github.com/labstack/echo/v4 to 4.15.2 or later

Other vulnerabilities in github.com/labstack/echo/v5