GHSA-p483-wpfp-42cj — high GitHub Advisory (CVE-2025-47269) in npm/code-server

Description

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/[email protected]/path would be proxied to [email protected]/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.

Basic information

Type: reviewed
Severity: high
Advisory on GitHub: Open advisory ↗
Repository advisory: Open repository advisory ↗
Source code: Browse source ↗
Published (advisory): 2025-05-09 19:34:35 UTC
Updated: 2025-05-09 21:39:17 UTC
GitHub reviewed: 2025-05-09 19:34:35 UTC
NVD published: 2025-05-09 21:15:51 UTC

Score	Percentile
0.33%	56.10%

CVSS Scores

Base score	Version	Severity	Vector
8.3	3.1	—	`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:L` Click to expand Attack vector (AV:N) Could be attacked over the internet or any normal routed network—not just someone sitting at the machine. Attack complexity (AC:L) Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup. Privileges required (PR:N) No account or special rights needed—anonymous or random user is enough. User interaction (UI:R) A real person has to do something—click, install, enable—otherwise it doesn’t land. Scope (S:U) Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems. Confidentiality (C:H) Serious risk that confidential data gets exposed in a big way. Integrity (I:H) They could widely tamper with or forge data—trust in the data is badly hurt. Availability (A:L) Might cause slowdowns, glitches, or partial disruption—not a full brick.

Identifiers

Type	Value
GHSA	GHSA-p483-wpfp-42cj ↗
CVE	CVE-2025-47269 ↗

CWEs

CWE id	Name
CWE-441	Unintended Proxy or Intermediary ('Confused Deputy')

Affected packages (1)

Vulnerable version ranges and first patched releases as published by GitHub.

Ecosystem	Package	Vulnerable range	First patched	Vulnerable functions
npm	code-server	< 4.99.4	4.99.4	—

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