# CVE-2026-118656: Echo: Open Redirect via Control-Character Prefix Defeating sanitizeURI


- **Severity:** Medium 6.1 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Fix available:** Yes
- **Published:** 28 Oct 2026
- **Updated:** 29 Oct 2026
- **Also known as:** DEBIAN-CVE-2026-118656, ECHO-e06f-d2f8-f714, GHSA-v753-g4cw-jm48, UBUNTU-CVE-2026-118656

## What is CVE-2026-118656?

CVE-2026-118656 is a medium-severity vulnerability in labstack echo, published on 28 Oct 2026. 

### Official description

Echo is a Go web framework. Prior to 4.16.0 and 5.4.0, sanitizeURI checks only the first two bytes of a redirect target before deciding whether it begins with an absolute-path separator pair. When AddTrailingSlash or RemoveTrailingSlash is configured with a redirect status, a slash, TAB, separator path form can evade the guard, be emitted in the Location header, and be normalized by a browser into an attacker-controlled host. This issue is fixed in 4.16.0 and 5.4.0.

Weakness: CWE-601 (URL Redirection to Untrusted Site)

## Which versions are affected by CVE-2026-118656?

4 open source packages ship an affected version, including github.com/labstack/echo/v4 and github.com/labstack/echo/v5.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `github.com/labstack/echo/v4` | Go | All versions | 4.16.0 |
| `github.com/labstack/echo/v4` | Go | All versions | 4.16.0 |
| `github.com/labstack/echo/v5` | Go | All versions | 5.4.0 |
| `github.com/labstack/echo/v5` | Go | All versions | 5.4.0 |

## How do I fix CVE-2026-118656?

Upgrade github.com/labstack/echo/v4 to 4.16.0 or later.

## Is CVE-2026-118656 being exploited?

There is no known exploitation of CVE-2026-118656 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-118656 and fix it if it is affected.

What it is: CVE-2026-118656 is a medium-severity vulnerability in labstack echo, published on 28 Oct 2026. 
Exploitation: There is no known exploitation of CVE-2026-118656 in the wild and no public exploit code.

Affected packages and fixed versions:
- github.com/labstack/echo/v4 (Go): affected all versions; fixed in 4.16.0
- github.com/labstack/echo/v4 (Go): affected all versions; fixed in 4.16.0
- github.com/labstack/echo/v5 (Go): affected all versions; fixed in 5.4.0
- github.com/labstack/echo/v5 (Go): affected all versions; fixed in 5.4.0

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-118656/ (Markdown: https://insights.sbomify.com/CVE-2026-118656/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-118656
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-118656
- OSV: https://osv.dev/vulnerability/CVE-2026-118656

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-118656/
Summaries are generated and may contain mistakes; the official description above is the record.