CVE-2026-118652 Echo: Reflected Cross-Site Scripting (XSS) via unsanitized JSONP callback in Context.JSONP / Context.JSONPBlob

What is CVE-2026-118652?

CVE-2026-118652 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, Context.JSONP and Context.JSONPBlob concatenate an unvalidated callback value into a JavaScript response. A route that passes attacker-controlled input as the callback can return executable script syntax, allowing reflected cross-site scripting when a user loads the crafted response. The vulnerable jsonPBlob path performs no callback validation or escaping, and exploitation requires an application route that exposes attacker control over the callback argument. This issue is fixed in 4.16.0 and 5.4.0.

Weakness: CWE-79

Which versions are affected by CVE-2026-118652?

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

How do I fix CVE-2026-118652?

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

Is CVE-2026-118652 being exploited?

There is no known exploitation of CVE-2026-118652 in the wild and no public exploit code.

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as DEBIAN-CVE-2026-118652, ECHO-b997-6e99-fafb, GHSA-h9g5-28mm-hx3g, UBUNTU-CVE-2026-118652.